I have told this tale elsewhere but what the heck ................
At HQ 1 Gp in 1981 I had a colleague who had been, in his youth, an Air Met. Observer.
The above is true, the remainder is a paraphrase of his story:
Whilst in uniform, with his nice M brevet, he was accosted by an elderly Air Commode who demanded to know what the M stood for, it being exceeding rare.
"Midwife, sir!"
"What!?"
"Lot of pregnant women on the trooping flights sir!"
"Carry on sergeant!"
I don't believe a word of it, but it made oi larf.