Sorry, grobace, I don't know when Puddy slipped the surly bonds. I only heard from someone else (can't remember who it was).
For those who never met him, Puddy was the spitting image of Gert Frobe (the German in 'Those Magnificent Men in Their Flying Machine'), with a rich British voice and a wonderful fighter pilot sense of humour. One of his favourite dining-in night tricks was to pinch a soda syphon and stuff it inside his voluminous mess kit trousers, wedged under his ample gut, with the end just hidden behind his fly. He would then engage some unsuspecting wheel in conversation, before saying "Excuse me old boy, must have a leak" before squeezing the trigger through his trouser pocket. The resulting sudden jet from his nether regions would usually electrify his victim; being the gent he was though, he never did his party trick in front of a WRAF.