The Royal Commission on the ancient and historic monuments of Wales is a government detective agency a bit like the FBI.

But unlike the FBI, the commission investigates the history of Wales and its records are open to everyone.

This week, how robots are giving history a new dimension at a North Wales quarry.

Netting the secrets of how ancient coastal communities trapped fish.

And the hidden history of an architect who created a Welsh style of building.

This isn't something from Dr Who.

This robot is helping surveyors from the Royal Commission to make the most detailed survey ever undertaken of an historic quarry in North Wales.

It's part of a project to record the remnants of the Welsh slate industry for future generations.

The Vivian Quarry isn't one of the biggest in North Wales, but it's about to become one of the best known.

The quarry itself is barely noticed by the thousands of visitors to the National Slate Museum below.

Situated at the foot of Snowdon, Vivian Quarry opened in 1873 and closed in the 1960s.

The Commission is creating an online model of the site before the remains disappear.

The Vivian Slate Quarry is a very extensive site.

You've got quarrying on seven different levels.

On each level, you've got a different array of buildings.

You got the inclines between the levels.

To survey traditionally would be very time-consuming and quite difficult.

The robot allows us to access areas quite quickly, and the laser scanner lets us collect a huge amount of data very quickly.

This is where high-tech meets history.

The first time a robot and laser scanner have been used by the Commission to survey a quarry.

Technology like this is giving a new dimension to the task of surveying.

We drive the robots with remote control.

So what sort of distance can that cover in terms of remote access?

It depends on the environment and all sorts of things, but typically a few tens of metres is fine.

For sites like this and for derelict buildings, which are often dangerous to go and survey into, this would be able to access areas we wouldn't be able to.

Yes, and we can mount a similar system on smaller robots as well.

Oh, right.

So you've got a whole range of robots that can be used for different applications?

Yes.

With the robot in place, the laser scanner on top is about to survey a winding house with unprecedented speed and precision.

We'll set the scanner to scan remotely, using the html interface.

Right, so you can actually do it all from this laptop?

Yes.

We'll start the scanner collecting data and pull that data across to the laptop wirelessly.

It takes about one-and-a-half minutes to get 5 million data points.

And in a minute and a half, we'll have a full 360 by 310 degree field of view scan from that location.

To give a full 3D scan, the robot needs to move to a second position.

The results are astonishing.

We're going right down into the data, so let's wait for it to regenerate quickly.

There you go.

If we want to, we can turn around and look up the slope.

We can see from the interior up.

And we can jump up to the top and see what somebody would have seen from that location.

We can spin back down, and that's what they can see from up there.

So, how long do you think that that might have taken you to do conventionally?

To survey the building, probably about a day, maybe a day and a half.

We wouldn't be able to get the level of detail.

So you would probably represent that with a few thousand points as opposed to 5 million points?

We wouldn't be able to get the complex geometry of things like the winding drum.

It gives you much more feeling for the actual object.

Sue needs to build a clear idea of the lives of the quarrymen.

But all she has to work with are abandoned relics.

Slate quarrying was one of the toughest and most dangerous occupations in Wales, just behind coal and iron in terms of accidents and injuries.

Like mining, the industry had a strong and distinctive culture.

To help her unpick the past, Sue spoke to Dr Dafydd Roberts, one of Britain's leading experts.

We are up here on level two of the quarry now, and we have got a blast shelter behind us.

Yes.

This looks rather like a blast shelter.

You can see how it's been very, very firmly built.

Very thick walls and a very thick roof.

The quarrymen would go in here for 5 or 10 minutes at a time, stand in here while the blasting went on in the Vivian Quarry nearby.

The second level also contains the original splitting sheds where the slate was worked.

These are open…

flint splitting areas.

Not sheds as such, but smaller areas where slate was split and trimmed.

So each of these little inlets, if we can call them that, would have had two or three men working within, splitting the slate slabs and trimming them to size.

And they'd be working here as part of a team, so the rest of the team were at the quarry working with the rock face, extracting the slabs and then the remaining members of the team turning out roofing slates.

And what would be the average number of slates that they would be expected to make in a day?

That's very difficult to answer, because it depended on the geology of the slate coming off the rock face.

And the sizes of slates being made.

But you know, on a very, very rough average, I'd have expected to see each pair of men working here producing 300-400 slates per day.

Something of that sort.

Nowadays the winding gear on the first level has been restored, but others have been untouched since the quarry closed.

What you have here is a wire rope wound around a drum.

Around that as well, at the far end, there's another wire rope wound.

A loaded wagon going down is placed on the traveller which carries it down.

The rope pays out, but pulls up empty wagons on the traveller on the parallel truck.

It's very fundamentally effective.

The wire rope, that's been there since early last century.

We are reasonably sure that this set of inclines from this place upwards hasn't been used since about 1910.

This quarry here we think closed in the early 1960s.

Most of these structures were abandoned well before the 1960s.

At the foot of the quarry is a pool some 60ft deep which is now used as a diving school.

The pool covers important sections of the old workings.

Sue isn't sure what's there so she's called in her boss, Steve Hughes.

So we've done a survey of most of the working levels for the quarry now.

But one area we haven't been able to look at is this flooded area down in the base of the quarry.

We've been starting to look at some of the historic mapping to see how that developed and what buildings were down in that level.

It all seems to be rather confusing trying to work out quite what is happening there.

We can already see, in the 1870s, there's a flooded pit here.

It's much smaller than the present area, I think.

We see a series of tramways, but whether any of these inclines, and quite what the level of the land is, it's very difficult to make out.

Later maps reveal further changes.

The only option is to take a camera underwater with a little help from the diving school.

The results are much clearer than expected.

In the other world down below, the old quarry workings are clearly visible, barely disturbed after all these years.

Another key element falls into place.

Here's the circular building that they were talking about.

The roof with these massive slate slabs, really thick.

Yes.

Well, it would need to be thick if it's a blast shelter.

But it's very like a powder magazine.

I think there are stories about storing powder there.

Perhaps it's a dual purpose structure.

Sue's quarry model will soon be available in a new online service from the Welsh Assembly Government called the People's Collection.

The Royal Commission is starting the People's Collection, which will be a website which will allow greater access to collections, and, most importantly, to interactive visualisations of different archaeological sites and artefacts.

So with the data we are collecting here using the laser scanner, we can actually produce fly-through views making the quarry accessible to people who can't physically come here and, from that, we can hopefully start to do reconstructions of the various working processes of the quarry as well and the buildings as they stood 100 years ago.

As the Royal Commission's aerial photographer, Toby Driver regularly takes to the skies over Wales.

Today, he's flying alongside the Pembrokeshire coast.

When he reaches Fishguard, he finds what he's looking for.

Below him, glistening in the depths of Goodwick harbour, is a fish trap, used in the past for catching fish without putting out to sea.

Toby's known about this for long time.

But his eye is caught by something on the other side of the harbour, a trap which has been hidden for over 60 years.

There's a lot about fish traps that we still don't know, and Toby has asked the Commission's Maritime Officer, Deanna Groom, for help.

I've seen from the air that there are two traps in the bay here.

The one on the north side is better known.

, isn't it?

Yes, it has certainly been marked on a map since the 18th century.

Oh, so quite a long time?

Yes.

This one hasn't.

It's not even marked on the Ordnance Survey maps, which is kind of curious.

It seems to have eluded all the map makers.

When look at our aerial photographic collections taken by the RAF in 1945-46, it appears on them then.

Then it disappears until your superb photograph put it on the map.

Was it covered with sand, or has something obscured it?

I think that's the story here, In the aerial photographs, you can see currents and sandbanks moving around in the bay here.

I think that when the first Ordnance Survey came here to map this bay, it was possibly covered up, and that is why it never got recorded by the Ordnance Survey.

The name of Fishguard is in itself interesting.

Does it refer to the traps in the harbour?

Fishgarth or Fishguard appeared around the early 13th century.

If they were connected to that story, the origin of name, then these certainly are over 800 years old.

Fishguard is famous for its herring industry.

That's all the recent history, the shipping and fishing fleets.

I wonder if we can take that back to when this trap was being used, what sort of fish were being caught a trap like this?

There are stories of these huge catches of herring at the fish trap at Rhos on Sea.

That's in North Wales, isn't it?

There's a story, in 1859 in one night, it caught 35,000 herring in one go.

That is an enormous catch.

The technology is phenomenally simple.

Fish come inshore as the tide comes in, and as they go out, the barriers are so designed and so located that they herd the fish into the catch net at the end of it.

Just looking at the aerial photography, they don't seem to have a gap in them anywhere for a sluice, where the fish would have been caught or the water let out, which is more of an interesting concept behind these two that they were more tidal ponds and the fish were retained in there.

Flying up the west coast of Wales, you see these characteristic V-shaped traps.

But there are also D-shaped and box shaped traps, and rectangular traps.

I'm not sure if that's different ages, different technologies.

These are very elegant, very sophisticated shapes when you look at them from the air.

It's got a very elegant little hook which is probably where the fish ended up, herded into that hook.

So that V shape, it's the apex where the fish are being caught.

That's the idea.

Toby has recorded nearly 100 fish traps around Wales.

His picture of a forgotten trap at Poppit Sands near Cardigan was picked up by national and international media.

Since then it's been investigated by Dr Ziggy Otto of the Countryside Council for Wales.

The Poppit fish trap is the largest I've come across.

It's 260 metres long, and it's different from the Fishguard one.

It's lower within the tidal frame and it acts nowadays as a natural reef.

Although it is an entirely man-made structure, it is now a lovely reef.

Red algae, encrusting honeycomb worms, which are protected, sea anemones.

It is quite beautiful.

Fish traps were stone walls topped by wood that snared the fish when the tide went out.

I envisage that, with the help of a couple of boats, maybe, and nets, you corral those shoal fish, such as herring and mackerel, into these traps.

And then to close it off as the tide goes out.

But I would not be surprised if it was also flat fish.

So it is not a lazy fisherman's device.

It is not waiting for the fish to come in here and potter out at low tide.

It is actually, as the tide is going out, that one is coaxing, one is pushing the fish into here.

Using it as a reservoir, almost.

You have to actively intervene.

This is not just a passive trap, where you come back every second day and find a few fish in here.

You wanted to fish this whenever you wanted.

Not just 12 tides a year.

You wanted this one to provide a constant food supply.

The trap may reveal changes to the sea level because today it is completely covered for most of the year.

You have to observe it through a tidal cycle to work out where low-tide was.

You would expect this point here to be the low tidemark.

The fact that it is now pretty much mostly underwater, again, it is indicative of the hot topic in the news at the moment, about changing sea levels.

Are we looking at something that may have been in use over 1,000 years ago?

So the fact that it's almost always underwater is indicative of sea-level rises over the past 1,000 years.

Changes in sea-level are a vital part of the Royal Commission's investigation brief, especially in terms of climate change.

If current forecasts are accurate, parts of the coast of Fishguard may disappear.

Current predictions are that, by the end of this century, there could be as much as an 80 centimetre increase in sea level.

Using that figure, I've been able to model the impact of that predicted climate change and sea-level rise.

Those areas in red that you can see now are most at risk from flooding?

It gives us a first glimpse of what impact there might be of climate change on the coastline of Wales.

Snowdonia is noted for its distinctive buildings, with features such as steep slate roofs and big stone chimneys.

It's a local style that fired the imagination of one of Wales's leading architects at the start of the 20th century.

Herbert North's legacy includes over 20 buildings in his hometown of Llanfairfechan.

Was he one of the first to create a distinctive Welsh style?

Adam Voelker is writing a book about one of his heroes.

As an architect himself, Adam is fascinated by Herbert North's legacy and is producing the book in partnership with the Royal Commission.

One of the reasons, to me, why he is important is that in these days of what you might call global expansiveness, when houses and buildings in general look the same everywhere, no matter where you go, there's something very distinct about North's work.

He was an architect who did work in a very small, confined area in north Wales.

And you look at his buildings and they are very distinct and very appealing to lots of people.

He is an architect who was inspired a lot by the Arts and Crafts movement but also, at the same time, by vernacular buildings in North Wales, particularly in Snowdonia.

Herbert North spent his formative years in London absorbing the influence of the Arts and Crafts movement.

This emphasised simplicity and tradition, qualities seen in an archive of North's work at Royal Commission headquarters in Aberystwyth.

Around 1900, North moved to Llanfairfechan in North Wales, where his family were landowners, and he started to build his version of an idyllic village.

Here was a lot of land that could be developed.

And being in the kind of circle that the Norths were, they knew teachers and solicitors and people like that, and here was an ideal place that North might create a sort of dream village.

It's a little bit like a garden village in its appearance, but in fact it's a private estate.

Yes.

It does look very much like a garden village but it would be wrong to make too much of a parallel.

These houses were designed for sale and for particular people.

Adam is showing North's first building at Llanfairfechan to the commission's Peter Wakelin.

It's clearly an apprentice piece, built of stone with sash windows, timber boarding and a conventional Victorian symmetry.

It was with his next house just up the road that North began to experiment.

These wonderful slate fences are very traditional parts of the landscape.

Yes indeed.

You see them everywhere.

And North was very keen on picking up on these traditional features.

This was North's second house locally?

Yes.

Date is 1899.

Here we are seeing already some interesting developments.

We see rough cast walls.

We see the eyebrow roof over the dormer windows.

That's a very Arts and Crafts feature, isn't it?

These curves are typical of Arts and Crafts, including the round window there and the round headed window upstairs.

Interestingly, they are features that North stops using.

He used them here and then moved away from that.

You've got angles like the chimney up there.

Yes, big chimney, set on the diagonal.

This is a feature of some of the higher class houses in Snowdonia.

It's a sort of halfway house where he is halfway between Arts and Crafts ideas and pushing those out to concentrate on Snowdonian examples.

North created the heart of the village at Llanfairfechan, building 26 houses in the close, all now listed.

The style evokes a golden age of village life.

His church institute is still used as a community centre.

It is complex and it is quite simple, in a way.

You see with these little wings, a wing for the ladies that side, they would come in that side, have their loos and so on, there, the men would come in this side.

In the middle we have the hall and the stage, the far end.

Some lovely details.

The diminishing course slates are beautiful.

Lovely coloured slate.

North was very keen on using slate.

It was the local material.

In fact these come from a small, unmechanised quarry at the foot of Snowdon.

The tiny ones at the top are absolutely beautiful.

Almost like oyster shells - they are so rough and thick.

Very small.

They've got the nice colour range from greens and blues through to browns and copper colour, so that it's a very lively roof.

And you see, also, a lot of it.

Look how much roof there is there, being enjoyed as it were.

North also designed several churches and chapels.

One of the most striking is Bangor University, which Peter visited with its chaplain, Kenneth Padley.

I cannot believe how small this church looks from outside.

It's tiny.

It looks small but on the inside, you shall see a bit more space.

You can fit everything in, can you?

Everything we need.

I love the walls, the feeling that this building's soaring up out of the ground, and these little ledges.

The pebbledash is something that we don't think of as being particularly nice these days, but he's used a lovely local granite which has that lovely, dark quality that matches the slate.

And the lovely coursing of the slates in those diminishing courses.

It's something he used on houses, and picked up from traditional buildings all round North Wales.

That sense of prayerfulness is possibly the most important thing that strikes people.

They're not expecting it.

It kind of seeps through the walls at you.

The air feels thick.

That is the number one bit of North's build that meets my priestly work.

And the decoration up there.

I read that North's wife often painted these.

It's very beautiful and in incredibly good condition.

My understanding is it's his personal gift and similar to a painting in the church in Llanfairfechan and his allegory on Jesus has the true vine fitting with the Eucharistic worship of the bread and wine on the altar below.

And nobody ever thought about painting it out!

But it is for his domestic architecture that North is best remembered.

Nowhere more so than at Wern Isaf, the home he built for his family at Llanfairfechan in 1900.

Now lived in by his granddaughter, it's regarded by many as his masterpiece.

Here we are at Wern Isaf.

The house was built by North in 1900.

This was built for himself and his new wife and they moved up here.

Fantastic rooms.

Really beautiful.

I think I can see in this house, things that speak to me of the vernacular tradition, and North really trying to create a modern interpretation of the Welsh vernacular.

We've got the wooden floorboards, the lovely oak, instead of mahogany.

We've got these great beams exposed in the ceiling.

Lovely deep window seats and shutters - very much a traditional, vernacular thing to keep out the Welsh weather.

And pierced, I see, with all these different patterns that are typical of the everyday man's ability to make a pattern, rather than something taken out of a Renaissance copy book.

And I noticed, outside on the way in, lovely dry-stone walls and a wildflower area of the garden which is keeping the house in the traditional landscape rather than creating something that is suburban or different.

I think you're quite right in picking up these traditional features.

But I actually see a lot that is not very traditional here also, and to me it is interesting how he combines both these vernacular things from Snowdonia and from North Wales in general with a whole raft of ideas of his own that he has brought up from his experience in London.

That looks to me like something you would never see in a Welsh farmstead.

You certainly wouldn't.

The idea of having the fireplace as the centre of the house, the hearth, that is all very important to Arts and Crafts' ethic of how you build a house.

What is interesting is this butterfly plan arrangement where you have got the sequence of spaces going through here from the living room, through to this room in the middle and then round the corner.

And what's really interesting and very cleverly done here, is that these three rooms can either be three separate rooms separated by these rather nice glass doors…

You can close these off, can you?

Swing those closed here.

Those two here, you can also close round.

So we then have three rooms here to be used as three separate spaces.

Or you can have them flowing through.

We are fortunate to be here on a day like today when the sun is out, all the doors and windows open, fantastic views out to Anglesey and Anglesey">Penmon, and so on.

I can see the sea, and beautiful woodland on this side.

And the air and the light all flows through and really makes sense of this glorious, glorious house.

It's a mark of his creativity that he's been able to respond to the site and have this wonderful feel of history and tradition and Welshness.

That's right, yes, sort of combining old ideas and new ideas.

If you're interested in Herbert North's work, his plans can be seen at the Royal Commission's archive at Aberystwyth.