These Dangerous Years

These Dangerous Years AKA Dangerous Youth is a 1957 British comedy musical film directed by Herbert Wilcox and starring George Baker, Frankie Vaughan, Carole Lesley, Thora Hird, Kenneth Cope, David Lodge and John Le Mesurier.

Tough gang leader and wannabee rock star Dave Wyman, from the slums of Liverpool, gets the call up for military service. He undergoes basic training, finds the discipline surprisingly suits him, and emerges stronger. When his best friend from training is killed by the camp bully, Dave takes revenge, and eventually ends up marrying his singing partner.

Source: Wikipedia