Watch as Jon Snow finally gets the chance to grill David Cameron on Tory election 'fraud'

David Cameron has accused Channel 4 News of “making a mountain” out of claims of Conservative fraud at the last general election, while admitting that the party tried to get a senior lawyer to stop the investigation in South Thanet.

The Tories have been accused of failing to declare spending on a national “battle bus” that was partly used to transport activists to key marginal seats – money that would have taken the party over the limit if it had been declared locally.

After a months-long investigation by Channel 4 News, Mr Cameron finally appeared on the channel to face presenter Jon Snow after a judge said the scandal could see “election results being declared void”.

The allegations raise the extraordinary prospect of a rerun election in the crucial seat where Ukip leader Nigel Farage was beaten by Conservative Craig Mackinlay by just over 2,800 votes.

The Prime Minister said he was confident his party had done “nothing untoward” in its use of the national bus, and defended his party’s attempts to hire a QC to block police from getting an extension to investigate the claims in South Thanet.

Mr Cameron said he was happy for the Electoral Commission to examine “all of this”. “It's very important all these things are investigated, I'm very happy for us to answer all the questions about it, I don't think that there are any questions that anyone is asking that we can't answer and... I think it will put it beyond doubt.”

Asked specifically about South Thanet, Mr Cameron dismissed it as just “one particular seat”. “There had been a year and it is perfectly legitimate to argue that is enough time to look at it,” he said.

“There is no point having a spat about this now,” he said.

Mr Cameron also disagreed with Snow’s assertion that the Electoral Commission “had to go to court to wring the papers out of you”, and responded angrily to the suggestion he was not taking the inquiries seriously.

The Prime Minister said he believed Channel 4 News was “making quite

a large mountain out of what I think is a relatively small point”.

He said: “I think it is a relatively straightforward set of questions that we have to answer.

“I'm very confident we're going to answer all of them and put this issue comfortably away. Because at the end of the day, as far as I can see, all parties have national bus tours, that's a national expense.

“All parties have associated expenses with those national bus tours, and I'm very confident that the party chairman and all the investigations will be able to answer all of these questions and... I'm taking it seriously because it's a serious issue but I'm confident that there's nothing untoward here.”