so you thought it was a genuine C15 S or scrambles bike. I thought it pretty much could have been any C15 just with that tank and no lights. Who knows what previous owners done to it and the item description doesn’t say much and sellers can claim the bike they are selling can be anything! If I was interested in it I would of definitely asked for the engine and frame number to see what exact model it was because it may not of been the genuine MX model. The trials models looks pretty much same as the MX model and has the same alloy tank but has lights as well. That could of also been the standard road model with that tank stuck on it. In the photos I didn’t really pay much attention to the tank to see it was alloy, but ive got one that’s a very similar shape in fibre glass which is a period aftermarket tank for C15 trials/mx bikes. I now know what you mean about the alloy ones being worth heaps. The genuine one on the B44 GP I’m restoring is the true GP tank with the push in bung type cap and when a customer saw it the other day he wanted to buy it but we said its definitely not for sale. Many people who build replica B44 GPs using Faber frames etc just use the victor enduro/special tank which is still alloy but has a folding type alloy cap and they are much easier to find than the GP tanks. You can actually buy replica/repro tanks from places like Sammy Miller in UK. That extra case on the right side of the C15 on ebay is certainly not original. As Firko says it looks like they changed it from a distributor to a magneto. I’ve never seen that as a factory set up in any of my many BSA books so must be a home conversion. That frame with that oil tank came out in 1963 so that bike would be no older than that. The exhaust originally tucked in behind the frame too. A lot of the small british bikes like the C15 don’t interest the general british bike fans as most are into the big 500-850 bikes but bikes like the C15/B40’s etc are becoming quite popular with the vintage mx/trials crowd so if you got one for sale but cant sell it you gotta get it advertised to the right market and the people who like those smaller offroad bikes will pay pretty good money for them. Pretty much all british offroad bikes are now desirable, highly sought after and collectable now, when several yrs ago you probably couldn’t give them away, so they shouldn’t be given away for cartons of beer anymore! Over all since the alloy tank is worth a couple hundred I think the buyer got a fairly goodish deal.