An estimated 22,500 police officers have marched in central London in a protest over pay. Officers are angry that a 2.5% pay rise has been backdated to only 1 December for officers in England, Wales and Northern Ireland. Prime Minister Gordon Brown said he would have liked to pay more but it was part of the "fight against inflation". The Police Federation, which represents officers, has applied for a judicial review of the decision by ministers. The Home Office said it had a responsibility to make sure pay rises were in line with government policy. But police say the rise is effectively a 1.9% increase, unlike Scotland where it has been backdated to 1 September.