In reply to your questions:The sign actually says Harold Hill CC which was a cycling club i belonged to near Romford, Essex.
and I can't imagine the hat would still exist as it wasn't mine and it was 35 years ago.
It was definately FUN motoring, i had 2 8" goodmans speakers connected to a pye car cassette player ('70s ICE)blasting out Led zepplin,purple,stones etc.
Cheers
Trev
Harold Hill, latterly known as Harry became a popular comedian and TV host who specialised in jokes about mash, lamb and made big shirt collars popular