The Jokers (1967) on Netflix

Oliver Reed and Michael Crawford play two brothers who are always trying to find some way to succeed with cleverness rather than simple drudgery. Crawford is constantly living in his brother's shadow as the one who gets caught. After Crawford is forced to resign from the army after an episode of unappreciated cleverness, the two decide their careers would go better if there was a large amount of publicity, so they decide to steal the crown jewels from the tower of London. Bombs, misdirection, disguises and acting allow them to enter the tower with all of the alarms turned off.