These rare early overhead cam Ariel Square Four motorcycles do not turn up in barn-find condition very often – actually they are pretty scarce anywhere outside museums. Out of my price range (barns aren’t what they used to be!) but a lot of very clear photos.

This bike looks pretty complete and the numbers match.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=260555028199

Update: bidding closed at US $26,900.00

Jings!