Fifty Ships - S2-E1
Factual error: In the scene when Foyle meets the Home Guard colonel, Letwin, the colonel, has his Sam Browne belt slung over his left shoulder which is totally wrong, especially for an officer risen to field rank. Apart from being intended to provide support for the officer's sword (even if not worn and even if his service revolver is likely to induce sagging), the belt slung over the left shoulder will obscure medal ribbons. Horror of horrors.
Fifty Ships - S2-E1
Factual error: One of the wall pictures in the departure hut in the penultimate scene appears to show passengers boarding a Comet jet airliner, introduced in the early 50s.
Answer: He doesn't actually wear it all the time even in summer. In some episodes in the summer he simply wears his suit with jacket.