Audience heckles prime minister as he defends NHS policy and laughs when he tries to explain his announcement that he will not seek to serve third term

David Cameron was subjected to mocking laughter by pensioners from Age UK as he sought to defend his surprise announcement that he would not seek to serve a third term in Downing Street.

The prime minister, who had earlier been heckled at the Age UK conference on Tuesday, said he had given a “very straight answer to a very straight question” from the BBC about his future.

Amid concerns among Tory MPs that he had undermined his own authority by laying the ground for the party’s next leadership contest, Cameron addressed the claim that he was behaving arrogantly by suggesting he would like to remain as prime minister until 2020 before voters have had a chance to cast their ballot.

The prime minister said: “I am taking absolutely nothing for granted. My entire focus is on the next 44 days and the general election that will decide which team runs this country for the next five years. I want that to be me and my team. But the alternative is Ed Miliband and his team.”

But the audience resorted to mock laughter as he recounted his conversation in his Oxfordshire constituency with the BBC’s deputy political editor, James Landale.

He said: “What I did in my kitchen is I gave a very straight answer to a very straight question. I think people will understand there – that saying you want to serve a full second term, a full five years is a very reasonable, sensible thing to say. That is what I did say.”

Conservative ministers seek to play down Cameron's third -term bombshell Read more

The prime minister spoke after pleading with the Age UK audience to allow him to answer questions from the media after he spoken about health and pensioner benefits. As members of the audience shouted “no”, the prime minister pleaded for them to agree a deal in which he would take two questions from the media.

The prime minister had a mildly hostile reception after he arrived a few minutes late for the conference at the Queen Elizabeth Conference Centre in central London. In his initial speech, he was relaxed, and even spoke of his political epitaph.

“I have got to be honest with you,” Cameron said. “I don’t want my political epitaph to read that I just balanced the books and cleared up the mess I inherited. I am here today because I want a different kind of Britain.”

But he was heckled as he spoke of how the government injected an extra £2bn into the NHS in the autumn statement in December to help ensure that hospitals were less reliant on agency staff. The prime minister was heckled when he defended the right of nurses to work for agencies in response to a question about the way in which NHS staff move to agencies to increase their wages.

Facebook Twitter Pinterest David Cameron speaks at the Age UK rally. Photograph: Dan Kitwood/PA

The prime minister defended his BBC interview as George Osborne and Boris Johnson – named by Cameron as his likely successors, along with Theresa May – led a frantic rescue operation. Senior Tories moved to shore up the prime minister by saying he had acted in a humble way when he announced he would not serve a third term in Downing Street.

The chancellor told the BBC: “I think it’s really refreshing that we have a prime minister who gives a direct answer to a direct question. He has said he’s going to serve that full five years. The question now facing the British public, as we approach this election, is do we want five years of strong leadership, with David Cameron delivering zero inflation and record jobs, or do we want the chaos and incompetence of Ed Miliband?”

The London mayor said Cameron had shown “sanity and reasonableness” by speaking so honestly about his plans. Michael Gove said the prime minister had made a statement of the obvious.

Johnson, one of three possible successors named by the prime minister, said Cameron had shown humility. Speaking on his LBC phone-in, the London mayor said: “To say he is arrogant or presumptuous to rule out a third term seems to me totally bizarre. Actually he is being rather humble and rather straightforward and telling him like it is. The prime minister ... is showing eminent sanity and reasonableness.”

The comments by Johnson echoed Michael Fallon’s remarks. The defence secretary had earlier told BBC Radio 4’s Today programme: “The prime minister made very clear he is standing for a full [second] term … what happens in 2020 really, I think, doesn’t bother a lot of people ...

“If he had said exactly the opposite – that he wanted to go on and on and he wasn’t prepared to answer the question when he was likely to finish – you’d have accused him, quite rightly, of arrogance and wanting term after term. He answered the question in an absolutely straight way. Ten years as prime minister is probably enough for anybody.”

The interventions by Fallon and Johnson marked the third – and finally the most successful – stage of an overnight operation by Downing street to close down a potential row after the prime minister astonished Tory MPs by announcing his departure and effectively triggering the start of a long race of succession.

Downing street initially said after the BBC interview was first broadcast at 6pm on Monday that the prime minister had merely confirmed that he would serve a full second term if re-elected next month.

Amid concern on the Tory benches and among ministers that the prime minister had undermined his authority by announcing his sell-by date, Gove made an unscheduled appearance on Newsnight later on Monday night. The chief whip said the prime minister had made a statement of the “bleedin’ obvious” but then suggested it was right for him to outline a timeframe for departure because US presidents serve fixed terms of four years, with a ban on a third term.

Fallon and Johnson finally crafted the line that Downing street hopes will help to draw a line under this row. This was to throw back the central Labour and Lib Dem line of attack by saying it would have been arrogant of the prime minister to suggest he would remain in office indefinitely.