I bought this on ebay long after I should have stopped. It was a gamble just like anything on there. I paid about £60 including postage and it arrived promptly and well packed. It seemed quite small when unwrapped, the short headstock surprised me but the measurement centre to centre was on a frame with relaxed angles, the vertical measurement is a fair bit less.
There is no indication that it is a BSA, why then did the seller suggest it might be? Looking at his other items, there were a couple of large flange chromed steel hubs engraved with BSA and which probably came off this bike. The number 69224 isn't really a lot of use, it seems Raleigh and Sunbeam can be dated easily but not Dawes or BSA.
Once I had examined the frame and forks, and impressed by what I had bought, I had a hunt round for which bits could be used to turn them into a bicycle. I had taken a Dawes down the tip; 500 CroMo is actually quite a heavy frame, the tube is quite thick-walled - and the frame was far too large for me. However I had kept the wheels and the calipers. This BSA probably took 26 by 1 1/4 wheels, whereas the wheels that came out of the Dawes were 700C. I offered the front wheel to the forks and it fitted, the axle was 8mm and the hub narrow! It was the only hub in my garage that would fit the forks; it gets better, the caliper's drop was perfect for the 700C wheel and the drop at the back matched too, both with room for mudguards. In many cases modern bikes are built with wheel clearances far too close.
The seat tube clamp bolt was seized so I cut through it and could see that the seat post entry was not circular, gentle persuasion with a lever and the seat tube opened up to 27.2 mm! The bike was described as a lightweight in the listing and I only know one tube which takes that size seat post, 531.
14-02-2016 More later.
30/06/2016 I've done a bit more work on the frame and discovered damage to the left hand seatstay, looks to be filled with lead. Never mind, I don't think the seller knew and it will still work - after all the bottom bracket threads are undamaged.