Conversation so far:
What did Spike Milligan write during the second world war?
During the Second World War, Milligan served as a signaller in the 56th Heavy Regiment Royal Artillery, D Battery (later 19 Battery), as Gunner Milligan, 954024.
How long was he there?
CANNOTANSWER.
did he write while there?
After his call-up, but before being sent abroad, he and fellow musician Harry Edgington (1919-1993) (whose nickname 'Edge-ying-Tong', inspired one of Milligan's most memorable musical creations, the "Ying Tong Song".

Question: What was it about?
Self-contained rewrite: What was Ying Tong Song about?