This graphic shows the make-up of this evening's audience. As the BBC's chief politics adviser, Ric Bailey, says in a blog post: “This means that each party leader faces the same prospect – an audience where one in four supports him, but where the majority does not.”

Mr Cameron says: "It was always there for me. I will always make sure it is there for other families". One of his big ambitions for the coming five years, he says, is a seven-day NHS.

Eddie McGinnis:

After creating so many jobs why has the deficit not fallen with an increase in tax take? Easy, because the jobs are low paid.

David Cameron says he wants to cut people's tax, calling tax "the biggest element" of the cost of living. He wants to "stop taxing poor people in this country".

Reality Check

David Cameron said that when the Conservative-Liberal Democrat coalition came to power some households were claiming £70,000 to £80,000 in Housing Benefit. A member of the audience asked how many households were claiming that much.

We can't answer that precisely, but the government released figures under the Freedom of Information Act, external showing that - of 4.7 million people claiming Housing Benefit in August 2010 - 400 were receiving more than £40,000 a year.

"I want to put it absolutely beyond doubt...I want (people) to know we are not going to put up VAT, National Insurance or Income Tax," says Mr Cameron.

Reality Check

A few moments ago, an audience member asked about the one million people using food banks. The Trussell Trust, which manages the UK's largest network of food banks, says that three days' food were given out 1,084,604 times in 2014/15, which was a rise of 19% from the previous year.

But this isn't the same as one million individuals using food banks - some people will turn to a food bank on several occasions.

In fact, the Trussell Trust says that on average people who used its food banks needed two food bank vouchers a year. If we use this figure for an estimate, then the number of unique users drops to around 500,000. There’s more in our Reality Check.

The prime minister says Labour's Ed Miliband will say the budget deficit should go on "forever". But an audience member asks why Mr Cameron can't debate with Mr Miliband directly? The PM replies that they debate directly in the House of Commons and that he feels what he's doing now is more "powerful".

Here's how that £209.4bn spent on welfare in 2013/14 breaks down: £11.4bn went on child benefit.

Asked why a million people in the UK have to rely on food banks, the PM responds: "I don't want anyone to have to rely on a food bank in our country. The most important thing we could do is to get more people into work."

The prime minister moves the debate to what he says the Conservatives have achieved. He says they have created two million jobs. But David Dimbleby takes him back to the proposals on child benefit. Mr Cameron says he "rejected" the proposals to cut child benefit.

But the PM shifts the debate again, saying there was no money left when he entered No 10. And he produces the infamous note left by the Labour Treasury Minister Liam Byrne, telling his successor there's no money left.

Find out where all the parties stand with our policy guides.

Challenged by an audience member on young people unable to work or stay at home, Mr Cameron says: "Anyone who clearly can't stay at home...we have to make special provision for them and we will."

Reality Check

David Cameron first faces questions about welfare payments. We know that the Conservatives want to save £12bn on welfare but we do not know how that will be done. The BBC's Michael Buchanan has been looking into how difficult that would be.

David Cameron says he does want to put to bed those rumours about child benefit and tax credits. But he adds that it's "important" to go on reforming welfare. He tells the audience that when he became PM some families were getting up to £90,000 in welfare.

Conservative Leader David Cameron is first up - his question from the audience: Will he put to bed rumours he plans to cut child tax credits and restrict child benefit to two children?