Downing Street cats Larry and Palmerston have had their "most brutal fight yet" according to a political photographer who is urging Downing Street to "take responsibility" for the spats.

Fur flew as the two clashed yet again on Downing Street, according to Steve Back who said Larry lost a collar during the latest encounter with Palmerston, the Foreign Office's 'Chief Mouser'.

Mr Back runs the Twitter account Political Pictures, which has been documenting their fights.