Is it only Round Table/Rotary that build and ride these things? The people in my photo are Horley Round Table (plus hangers on) on their way to Horley Carnival. They had discs on their arms spelling out some phrase or other. This went a bit awry when they swapped seats. I see yours, Johnny, are also Tablers.
By huge coincidence one of my friends phoned last night for a chat, about an hour before I scanned that photo. Peeering at it closely I can see he's on the bike, sporting a dodgy headband. His brother, who was in RT at the time, is also in it. It was his funeral last week.