This is a very good, comedy, crime British movie from 1955.
The actors include Alec Guinness and Peter Sellers.
A gang of British criminals rents a room in a large old house, that an old lady owns and lives alone (except for a gang of parrots), in. They pose as a group of amateur string quartet musicians, who practice their music at the house. They actually play a record while they plan the heist of an armoured truck, carrying cases of cash money.
You probably will have to use a Torrent to acquire this movie.