How to be a total geek in central London. 1. Walk along High Holborn and, just round the corner with Gray’s Inn Road, approach this post box. 2. Nonchalantly point out, to whomever you’re with, that it’s the only post box in London to carry two Royal Cyphers — the symbols of Edward VII and Victoria. 3. Bask in the tepid glory that comes with being the God of Useless Trivia.