The Good Die Young (1954)
I watched this many years ago, long before TPTV, but wasn't sure to start with and it was only in the last third that I convinced myself I had seen it before.
Good film actually, which starts off with three men (one Yank and a Canadian "Yank" this time) with a fourth (Laurence Harvey, who was always good at playing parts of somebody who is sinister and off their rocker) who is the leader/organiser in a big old Jag about to commit a robbery and when the leader produces a case with guns in it, they start to get edgy. The film then shows the back story to each of them and how they came to be desperate, reluctant participants.
The end of the film then shows the robbery taking place with Harvey going menacingly over the top and the subsequent debacle they then find themselves in.
Very pretty and young looking 21 year old Joan Collins plays the love interest of one of the men and there's Mr.Partridge (Hi De Hi) Leslie Dwyer again.