Hot weather transforms London. From my vantage point of the top deck of a sweltering bus, I have just witnessed grown men paddling in the fountains at Trafalgar Square, and - most bizarrely - the Changing Of The Guard, complete with 20 Elvis lookalikes in white rhinestone-encrusted jumpsuits. I can only imagine the reaction of the American tourists: "Gee, honey, look: it's the King!"