I have had a look in my birmingham scott records and can find bikes fitted with engines either side of the one for sale,(DPY 5531). It may have been in a bike,but usually the head would be the “square type”,not the rounded (Shipley) type on this engine. It is most likely a leftover from the old scott stuff bought by Matt Holder. Some years ago i bought one of these new(old stock)engines for my brum.,it too had a “Shipley”head. Just popped out the garage to check the number
DPY 5513 !!!!!! spooky!. Regards Geoff.