Cameron 'treating people like fools'

Mr Clegg said the Tories should spell out how they would pay for tax promises such as proposals to reverse part of the Government's planned increase in NI contributions. "Any increase in taxation is unwelcome, but that is not the issue," he said.

"The issue is what can you do to change it, and what I think that people now know is that you can't have something for nothing and David Cameron is treating people like fools.

"He thinks he can promise the earth and not spell out how they would pay for it. I think those days are over."

Mr Clegg was speaking in the Hampstead and Kilburn area of London where he met Liberal Democrat activists and launched one of two battle buses for the party. He told reporters that he wanted to "get on" with the general election and that the British public felt "let down" after 13 years of Labour.

Mr Clegg was in Hampstead and Kilburn in north west London to give backing to Liberal Democrat prospective parliamentary candidate Ed Fordham.