We went to the British Museum to see the whole of this exhibition, The Tomb of the Unknown Craftsman, but spent so long looking at the bike we ran out of time to get into the main show. We're definitely going back - but check the bike!
The whole thing was custom made, with Grayson's own teddy bear, Alan Measles, riding in his own shrine on the back. Actually Alan was replaced by a stunt double who had to be auditioned…but you can read about all that here
Grayson himself seems an amazing bloke. I don't think anyone like him has ever existed!