Discussing the issue of public spending on policing, the Conservative leader said it was important the public see the value from public services equivalent to the amount of money they put in.
He added: "The Metropolitan Police has 400 uniformed officers in its HR department, when our police officers should be crime fighters, not form fillers."
The three political leaders also debated the issue of pay for armed forces personnel. Liberal Democrat leader Nick Clegg said: "The Army is underequipped and underpaid - we have to provide our brave service men with proper pay.
"It is a scandal that an army recruit earns £6,000 less than a new fire fighter."
Cameron added that the Government does not do enough for the army and focused on training for the Territorial Army.
The prime minister, Gordon Brown, concluded this part of the debate by adding: "We must ensure pay will rise for our armed forces. We need to get them security, homes and, of course, jobs when they return [from war]."
ITV, the channel that televised the debate, asked a sample of 4,000 members of the public which leader won the debate and Clegg came out as most popular with 43% of the vote, followed by Cameron with 26% and Brown with 20%.
