Who is the best-selling writer in history after Shakespeare and the Bible? The answer is Agatha Christie who was born in Devon in 1890 but whose stories often feature London and who wrote what is the capital’s (and the world’s) longest-running play The Mousetrap, which is still playing at Saint Martin’s theatre sixty-five years after it opened. One of the original cast was the late Sir Richard Attenborough, who was paid partly with a share of rights from the play. These were never expected to be worth much but later in his career he was able to sell them to help finance his film about the life of Mahatma Gandhi starring Sir Ben Kingsley.

Most London Blue Badge Tourist Guides have had clients who want to get a snap of themselves by a red London phone box, often with Big Ben in the background. It is almost a rite of passage for a visitor to London and so the red boxes at the end of Whitehall often have long queues of people waiting outside for the chance to take a picture of themselves. The phone booths are rarely put to their original use – namely, to make phone calls. Now, of course, the mobile phone reigns supreme and most people have a smartphone in their pocket.