I emailed the seller last week about this project. The forks are BSA WM20 from 39-45, gearbox is 1930's, front hub is 1930's Enfield, back brake plate is Enfield 1950's, Engine is a Morgan 3 wheeler type Jap engine (The cylinder head cooling fins run across the head which is against the air flow for a bike engine), the foot rest is a 1930-50's Enfield and the frame is a very profesionally made custom frame. I also suspect the tank to be a 1920 Enfield item but not sure. I'm not sure how this bike would be registerd because no club can date or or prove its provenance. I suspect that the high price is due to the Engine, these engines can sell for upto £2500 so I would assume the buyer will want the engine and get rid of the rest.
Oh, and the seller didnt reply, I dont think he liked the truth too much, I suggested he would be better of selling items individually as anyone intrested in smaller bits will lose out because of high bids for the engine.