So what sort of rock art would you get in other parts of Scotland or indeed other parts of Britain that you wouldn't necessarily get at the Ness at Brodgar and then I suppose vice versa?

Well, let's start with the Ness just to kind of summarise the carvings at the Ness.

I mean, they use a range of techniques, both a technique we call pecking, which is basically repeatedly striking the rock surface with a hard implement to create little marks which eventually create a shape.

So we have pecking, we have pick dressing, which is just picking the surface of a stone to kind of change the texture and look of it.

And a lot of incised carvings as well at Ness.

And the carvings, the form of the carvings, they're all abstract so that they're not representational of anything that we can identify today.

And they're very much linear in their focus.

What should people who maybe don't have that trained eye be looking out for to see if they could maybe spot rock art for themselves?