Um...is there any "native" London stone?

I'm thinking of visiting a couple of such lesser known stones and ancient sites in what was Middlesex that were mentioned in an article in the Spring/summer 2003 issue of '3rd Stone'. It's all a bit 'bottom of the barrel' but beggars can't be choosers.

I haven't yet heard anything about one in Chiswick (which is part of the Borough I live and work in - i.e. Hounslow) but there is a sarsen that has been erected in Lampton Park (Central Hounslow) right next to where I work. I haven't added it to TMA because it was a sarsen that was found and then erected in a park (and presumably erected very badly as it is being held up by an ugly bracing made of red bricks!), so I guess no-one knows if it was ever of any human significance. What do people think? should I add it?

Middlesex / West London does have a lot of history attached to it, ranging from large levels of flint and stone axes around Yiewsley to the Iron Age Boar figurines and wheel cymbol found in Hounslow and now in the British Museum, but getting any perspective of what life was like around here is hard with such large-scale modern development.

Oh come on, let's have some contributions on London sites / possible sites

we are all getting very lonely here.....

according to Christopher Chippendale in 'Stonehenge Complete'...

"Another single sarsen,blackened by smoke, stasnds in Hyde Park just east of the Serpentine, a forgotten relic of a 19th century bridge of sarsens"

I haven't been to the park since reading this, so I can't give any better idea of exactly where to look, but I think it shouldn't be too hard to spot when you know it's there.

For those who know the area, I have a question. There is a very old looking stone set into the pavement just outside the KFC on the south side of Gray's Inn Road (right where Gray's Inn meets the Pentonville and Euston Roads). It's roughly rectangular in shape, about 18"-24" tall, and around 12" wide on each side (these are just rough estimates - I didn't measure it). Anyone have any ideas about it? Someone has taken the trouble to set it here, and/or fit the paving around it. I'll try to take a photo next time I'm up there.

Call me naive (or whatever), but I've noticed how deep the R*man remains are in London (central London anyway), and I can't help wondering... wouldn't anything prior to them be even deeper still (if it was there at all)?