I've been to Brighton, too. It was in July 2006. London was unbearably hot, 34 C. You don't want to be in a big city when it's hot like that. My wife and I took the train from London to Brighton and spent a day by the sea. I had fish and chips, too. It was 27 C in Brighton. The ocean temperature was 14 C. A little too cold for swimming, which is why I didn't go.
Incidentally, ocean temperatures being like that even during heatwaves is the reason why England is, on average, has cooler temperatures than Finland in July.
Oh interesting. Yeah the water is always cold here on the North Atlantic, even during heat waves.
I was in London in 2006 and remember the heat waves we had sometimes before the financial/property crash of 2007 :)