Twenty years ago, on September 6, 1997, a coffin was wheeled through the streets of London on the back of a gun carriage. Within the coffin were the mortal remains of Diana, Princess of Wales, who had died in a car crash seven days before. The funeral followed strict royal protocol, but what was not planned was the astonishing size of the crowds that flooded the London streets, squares and parks. It was estimated that more than one million people turned out to witness the procession. It was one of the largest crowds to appear in England since World War II.