Describing a film as 'lightweight' shouldn't always be seen as a criticism. Two Way Stretch deserves the description, but it should be seen as praise rather than a put-down.
Back in the 50s and 60s, the British film industry seemed able to churn out these comedy films at the drop of a hat. The Ealing Comedies are the best known, but there are also any number starring Norman Wisdom, and also a few gems with Peter Sellers in them.
Sellers takes the leading role here, that of a criminal in the last weeks of his sentence. He and his three cell mates are drawn into a daring robbery - one that involves them breaking out the night before their release, then breaking back in again, thereby ensuring they have a watertight alibi. Just about every character in the film is a caricature - the kind-hearted chief warder, the bumbling prison governor intent on seeing only the best in everyone, the army chief in charge of moving the jewels. Yet it all works, so long as you don't go in expecting some significant piece of cinema.
An excellent cast, with Sellers on top form. Maurice Denham, as the governor, Lionel Jeffries, as the control-freak warder, and Wilfred Hyde-White, as the crook planning the robbery, are worth singling out.