Question: Why does Foyle wear an overcoat at all times of the year? I know that the English summer is temperate, but always a long, floppy overcoat?
Question: Why in the episode of the unexploded bomb in a children's playground was the bomb referred to in weight using kilograms? Did they refer to bombs in the 1940s in kilograms or pounds? (01:14:34)
Answer: They are using the accepted names of the bombs. During World War 2 the Germans used the metric system and produced bombs ranging from 50kg to 2500kg. Referring to the weight of the bombs in pounds (or fractions of tons) risked confusing the situation and would require someone to understand how to convert from imperial measures to metric, not an easy thing to do when under stress.
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.