Wearing shorts and knee pads, and with his faced smeared with mud, David Cameron raced through an icy stream as he competed in the Great Brook Run.

The prime minister crawled under a bridge and stumbled through the water to reach the finish line in the Cotswold village of Chadlington. He received a pint of ale and a medal for his efforts. (The event's website promises that every runner "no matter how crap" gets a medal.)

With the 2015 general election campaign expected to be tough, perhaps he was getting in some training for a dirty battle.