Henrik Right on both, I suspect! "longers" is indeed kids slang for their first long trousers. Hidden compo (compensation) has a good plausible ring to it. I may get a chance to look up the words over the next few days.
The "gingerman" was an American ex-GI who studied (if that's the word I'm looking for) at Trinity College Dublin around 1950. His real name was Ganor Crist - or thereabouts.The author JP Donleavy wrote a notorious book based on his life and times, under the title "The Gingerman".
Regards