The BBC was taken aback by leftwing attacks on its general election coverage, Fran Unsworth, the broadcaster’s head of news and current affairs, has admitted in a frank assessment of the political pressures that are undermining efforts to preserve the licence fee.

Unsworth, 62, said attacks on BBC standards of impartiality from sections of the political left, as well as from rightwingers, “was a Brexit thing”. “When you get a binary referendum choice that re-frames politics, people take sides in a way that they don’t in normal times,” Unsworth said.

Describing the latest government warnings about future funding of the corporation as “a serious threat”, Unsworth said: “We tend to get caught up in the maelstrom. If people don’t see their own ‘truth’ expressed, then they see it is an untruth. And social media now means that narratives can take hold that are not based in fact.”

Unsworth was speaking out after the appointment last week of Oliver Dowden as secretary of state for culture and the arrival of Julian Knight as the chair of the parliamentary committee that scrutinises the BBC. Both are promising to question the broadcaster’s reliance on income from the licence fee.

Criticism from those on the left who detected a rightwing prejudice in the BBC’s election coverage was a surprise, she admitted. But Unsworth rebutted claims that the attacks had been caused by a deliberate BBC attempt to avoid more conventional accusations of liberal bias inside New Broadcasting House. There had been no over-correction: “We just carried on doing what we were doing.”

Unsworth said she thought renewed hostility from the new Conservative government was unlikely to win back alienated former BBC support on the left.

“People are quite entrenched in their views on this, I think. We have just got to keep restating our case that we will listen to everybody, serve everybody and host everybody, but not be bullied by either side. We don’t get it right all the time, obviously, and people can be unhappy with what we do, and that is fine.”

The former World Service boss, who also has a seat on the BBC board, made her case for the defence following public arguments made last week by Sir David Clementi, her chairman, and Tony Hall, the director general, who both underlined the breadth of service the BBC can offer because of its licence fee income.

Unsworth said that in the run-up to the renewal of the terms of the BBC’s charter in seven years’ time, there was always bound to be a national debate, whatever the government.

“But all this talk about the future of the licence fee really should start with discussion about what the BBC is for,” she said. “Once you have answered that, you can go on to how it should be funded.”

Switching to a subscription payments would be unfair, Unsworth argued, because those willing to pay would end up funding a service that is still obliged to try to inform and reach the entire British public, according to its charter terms.

“This is where the whole subscription model starts to come adrift. If you have a national civic function, you cannot then choose for only certain sections of the audience to pay for it,” she said.

Unless the charter is radically altered in 2027, the BBC’s “universal mission” in not a consumerist one, but a key duty to keep the people informed, she argued. “Under our charter, the job is to provide impartial news without fear or favour, and not to be beholden to commercial or political interests.”

Facebook Twitter Pinterest The gender pay gap scandal, Fran Unsworth says, is a running sore at the BBC. Photograph: Mark Thomas/REX/Shutterstock

The BBC’s “civil contingency” function is also in danger of being forgotten, Unsworth believes. Aside from providing news – “public purpose number one” – the broadcaster must offer guidance in case of national emergency. She had recently witnessed this working in Australia, she said, when ABC regional radio services were relied upon during the power cuts caused by dangerous bushfires.

After two years in the top news job, Unsworth is now meeting criticism from inside her own organisation. High pay levels among senior staff – her salary is in the “up to £249,000” bracket – have prompted censure as 450 job cuts were announced last month across reporting teams. She and her colleagues accept this level of scrutiny, she said. “It is fair that the BBC gets more attention, because we should be better than others. It is hard, but fair enough.”

Her restructured, or slimmed-down, news service will be trialled next month, Unsworth said, explaining that it is designed to stop duplication and to give BBC reporting greater impact across all its channels, websites and radio stations. It will also make required budget savings.

She sees the gender pay gap scandal as “a running sore”, she added, describing it as “a legacy of yesteryear”. Journalists Samira Ahmed, Carrie Gracie and Sarah Montague were among those who found they were paid less than male counterparts. “We have to work through all this and put structures in place that avoid us getting into this mess again.”

Julian Knight said this weekend that criminalising those who do not buy a television licence but use the BBC is out of date: “When we’re looking at a world of populism, a world in which elites are being challenged an awful lot, the idea of criminal sanctions over the licence fee sticks in a lot of people’s throats.”

But Unsworth regards such attacks as a conflation of two separate debates – one about the decriminalisation of this offence, the other about the fairness of the licence fee. She cited the words of John Bache, national chair of the Magistrates Association, who earlier this month told Today programme listeners that a change “would make an insignificant difference” to levels of court congestion.

Another irritation for Unsworth is the growing assumption that the BBC has lost its youth audience due to technological changes. In fact, she argues, this has not happened yet and a good percentage of young people still watch news broadcasts such as BBC One’s six o’clock bulletin, which has pulled in audiences of more than 5 million since Christmas.

“We do see a slide in linear TV and radio consumption in the under 35s, it’s true,” she said. “And those behaviours will probably be extended to the under 55s eventually, which is why we really have to think hard about ways of reaching them. But it really is not a crisis.”

When Hall’s replacement is selected by Clementi this summer, they must champion all these arguments, and more. Yet Unsworth still believes the BBC’s best defence will come from its listeners and viewers: “Our real value lies in audience appreciation of what we do, rather than us simply banging the drum.”