Cameron tells TV he nearly gave up politics

In a highly personal interview, Mr Cameron said that the loss of Ivan, who was born with a rare condition which caused epilepsy and prevented him developing, was "very tough" and made him question the future.

But he said Ivan brought "great joy and happiness" to him and wife Samantha during his short life.

Appearing on ITV1's Tonight: Spotlight on the Leaders, he was asked if he felt like "packing it all in" after Ivan's death aged just six.

Mr Cameron said: "Yeah, to start with I thought, 'To hell with everything'.

"You do, it's just such a shock you can't really come to terms with it to start with.

"But, bit by bit, you start to think, 'Well, I need to get on with my life'. And to me my life is politics, it's public service, it's what I do, it's being a Member of Parliament, it's wanting to make a difference. That's what I want to do."

Mr Cameron led his party on the campaign trail yesterday with a scathing attack on Labour's election tactics in Loughborough.

Ahead of the launch of his own manifesto, he said the General Election campaign had so far failed to engage millions of people and blamed Labour's "scare tactics".

And as the Tories launched their next wave of election posters warning that Gordon Brown would repeat his "failures" if re-elected, Mr Cameron cited the example – which has been denied – that Labour targeted cancer patients with literature warning of cuts to the health service if the Tories won.

He said: "The Prime Minister says he has got a moral compass. He should get it out and look at it, and make sure those leaflets are withdrawn."

The posters build on the brutal "Vote for me" campaign – this time with a picture of a smiling Prime Minister alongside slogans such as: "I took billions from pensions. Let me do it again."