This little girl is about Ed Miliband's age, though. Maybe she's Harriet Harman's younger sister?
Anyway that's enough topical references. The picture comes from the annual Carnival event in Wellington, a smallish town near Taunton in Somerset. On a Saturday night in September, locals line both sides of the road, from one end of the town to the other, to watch a procession of floats, dancers and assorted performers. Watchers are invited to throw money into the floats as donations to local charities. If I remember right, this girl was part of the 'Over the Rainbow' float, and very colourful it was, too.