The Notting Hill Carnival – one of the world’s largest street festivals – kicked off on Sunday with Children’s Day. The three-day extravaganza is expected to attract up to two million people over the bank holiday weekend.It was originally launched in 1959 by post-World War II immigrants from what were then Britain’s Caribbean colonies, following violent race riots. This year’s theme is “Unity and Diversity” in the wake of the July 7th attacks on London in which more than 50 people were killed. Organisers have promised this year’s event will be bigger, better and safer than ever before. Extra tight security has been put in place to ensure the event runs smoothly. The festival’s famous parade with its colourful floats and dancers takes place today. The party is expected to last late into the night.