It’s not only Mr Wallingfield who has woken up here’s Mr JTG! He’s picturing a better Spraymobile than mine as well! I can send you a PDF of the manual if you like, a couple of changes from my 1958 one:
1. Two rear wheels, mine has one,
2. Looks like an F15 engine, mine has an Mk12. Your engine could be badged BSA..