Last week saw the anniversary of the one of the strangest and little-known tragedies in the history of London. It’s difficult to discuss sensibly: often, when people first hear of it, they can’t help laughing at the circumstances in which eight people – all women and children – met violent deaths. Time has helped dull the edge of tragedy of course, but even so, it seems awful for sane, balanced, kind people to find such a tragedy funny. But laugh they do.