In the real London it is not entirely uncommon to find yourself in a conversation with American tourists where they're asking/complaining about "military time" on train timetables. The odd thing about it being most platforms have a countdown-style timer much like you'd find in a US metro system.

I understand that sometimes they're just trying to interact with locals while on vacation, but it always seems like an odd starter. Depending on my mood you'll get a friendly chat about time displays¹, or a curt "it says 2 minutes 'til next train".

1. 24hr analog clocks worth visiting https://en.m.wikipedia.org/wiki/Shepherd_Gate_Clock , or metric time, or Swatch time, or ... I'm just as boring with strangers as with friends ;)