The legend is that Acker started learning a borrowed clarinet in the Army while doing his National Service.
Because of a navigational error with a truck he got sent to the 'glasshouse' ( otherwise 'quod', 'chokey' or, officially, 'the guardroom') which gave him several weeks of spare time...
I seem to remember reading that, having got a clarinet on official loan from the Army, he then used the classic services dodge of drawing spares from the stores to replace 'broken parts', sufficient to make a complete second instrument - the first one he handed in when he was 'demobbed'...
So taxes spent on the armed forces aren't all wasted...