Yank title Operation Snafu (had to be changed for them, cos they would have thought it was about a violin player!)
Set at the start of WWII, Alfred Lynch (I'd forgotten about him) as a chancer who is "forced" to join the RAF by a court, where he continues his fiddles, aided and abetted by a thick heavy in the form of Sean Connery.
Primarily comedy that has a serious moment near the end, but no gut busting humour, despite a roll call of British acting talent:- (with the American comedian Alan King playing a wise guy GI)
Victor Maddern, John Le Mesurier, Eric Barker, Cecil Parker, Graham Stark, Patsy Rowland, Jack Smethurst, Eleanor Summerfield, Miriam Karlin, Bill Owen, Wilfrid Hyde-White, Barbara Windsor, Stanley Holloway, Kathleen Harrison, Liz Fraser, Hugh Lloyd, Philip Madoc ("your name vill also go on zer list"), Arthur Mullard, Lance Percival, Anton Rodgers and finally, one surprise for me was Michael Sarne as a German soldier - still alive it seems (and older than me!) he will always be remembered by me for his 1962 pop record "Come Outside" with Wendy Richard as the Dolly Bird - it was sometimes played as the last song at dances in those heady days of the sexual revolution, so you could have a grope before you take her home to see if you could get past No.2. 
https://www.youtube.com/watch?v=pnTQT9Wbjk4
*EDIT Here's another from 1963 - Susan Maughan PHWOAR 
