Among the most esoteric hobbies known to mankind, train spotting ranks high. It often entails spending days in freezing cold, waiting for fleeting images of railway locomotives and ticking off their numbers in a little book. The aficionados of the cult are variously known affectionately as puffer nutters or anoraks. Surprisingly, they are known as “Pufferküsser” (puffer kissers) in Germany, and “foamers” in the USA — a term which nicely encapsulates the essential tad of eccentricity…