BBC political editor says it is hard to know if PM’s comments were a joke or veiled threat but that they added to pressure felt by corporation’s staff

David Cameron threatened to close down the BBC in comments made to journalists on a campaign bus during the election, according to the corporation’s political editor, Nick Robinson.

Robinson said it was hard to know whether the comments, which colleagues who were on the bus relayed to him, were a joke or a veiled threat. But the journalist, who faced sustained criticism from Alex Salmond during the Scottish referendum campaign, said they had had a real impact on the organisation and added to the pressure felt by BBC staff.

Some people on the bus regarded it as funny but they generally didn’t work for BBC

Senior Tories piled pressure on the BBC during the election campaign by commenting on its coverage and on the broadcaster’s future as it approaches negotiations over its next charter.

Tony Hall, the BBC director general, said on BBC1’s Andrew Marr Show on Sunday that there was “broad agreement” that the licence fee model of funding the corporation could be reformed but that it had at least “10 years of life in it”. He also indicated that changes due to be announced later this summer would help to simplify the BBC.

In an interview with the Guardian, Robinson said he had “thought quite a lot” about Cameron’s comments since first writing about them in his recently released book about May’s election. He said they had been interpreted by BBC staff as a veiled threat and “another bit of pressure”.

Robinson said his sources on the Tory bus said Cameron had responded to a BBC story about something he allegedly told his deputy, Nick Clegg, calling it “rubbish”, before going on to say: “I’m going to close them down after the election.”

Though Robinson has written that it is impossible to know whether Cameron’s comments were a threat or joke, he said the impact on BBC staff was real. “What really matters is the impact it has on other people,” he said. “Some people on the bus regarded it as funny but they generally didn’t work for BBC. The people who did [work for the BBC] regarded it as yet another bit of pressure and a sort of sense of ‘don’t forget who’s boss here’.”

Robinson said he agreed with the director of news James Harding’s recent comments that the BBC faced pressure from all political parties, but that Cameron’s status gave the words more weight. “The difference of course is that the prime minister is the prime minister,” he said.

“We didn’t know at the time, of course, that he would carry on, but given that that was a possibility, given the timing of charter renewal … it’s quite a thing to say.”

Robinson said comments “dropped into conversations publicly and privately” by other senior Tories, such as the former culture secretary Sajid Javid’s remarks about alleged BBC bias, added to the effect on staff.

However, he said he did not think the Conservatives wanted to scrap the BBC. “The Tories’ attitude and Cameron’s in particular is …, rather like their attitude to the Church of England. They are delighted it exists and regard it as vital to the fabric of England, but they also find it really annoying.

“I’ve never met a senior Tory who wants to close down the BBC,” he added. “I could be proved wrong … [but] I don’t think the BBC will get closed down.”

Asked to comment on Cameron’s remarks during the campaign, a No 10 source said: “This is total nonsense.”

Robinson accused Salmond, the former SNP leader, of an “utterly calculated” attempt to influence the way he and his BBC bosses covered last year’s independence referendum, after he reported on threats from the bank RBS to pull out of the country in the event of a yes vote.

He said he faced online abuse from “cybernats” – Scottish nationalists who objected to his coverage of last year’s independence referendum – and the poor relations with pro-independence supporters prompted the BBC to provide him with a bodyguard.

Robinson returned to the BBC for its election coverage shortly after surgery to treat a tumour on his lung.

Hall, in a wide-ranging interview, said mooted changes to the licence fee regime – from decriminalising non-payment to making television free for the over-75s – could have a serious impact on funding for the corporation.

But the director general left the door open to changing the way the fee is collected because of the increase in people watching catch-up television, for which they do not need to pay.

“There is a broad agreement that the licence fee should be reformed in some way to make sure everyone’s paying equally for it and I’ll go along with that,” he said, before defending the universal fee. “By everybody paying something we all get great services for less than if we go down the subscription route.”

Asked by Marr whether he was going to do something about the high number of middle managers, Hall indicated that a restructuring would be announced later this summer. “When I came here I said that I wanted a simpler, more straightforward, easier BBC,” he said.

Hall welcomed the appointment of John Whittingdale as culture secretary, saying that he “knows the sector” and “loves the BBC and the arts”. Whittingdale has previously insisted that the BBC stop producing highly popular shows such as Strictly Come Dancing, but Hall said: “I don’t think we’re there to be a market-failure BBC.”