While sections of the left object in principle to any platform being given to the far right, much of the criticism of the BBC’s decision to screen an interview with Marine Le Pen focused on good taste as much as political judgment, the interview with the French far-right leader falling on Remembrance Sunday of all days.

The BBC is, of course, no stranger to such political furores. It previously came under criticism over the appearance on Question Time of BNP leader Nick Griffin in 2009. Like the present controversy, that was an extreme case that rightly received considerable attention. More worrying and less discussed is how the BBC’s daily reporting is skewed in favour of conservative movements and business interests – a bias that is rarely challenged. Conventional wisdom has it that BBC political reporting is impartial, or even left-leaning. This makes sense if your comparison is with the Sun or Daily Mail. But closer scrutiny reveals a less comforting picture.

Taken in narrow terms, the BBC is assiduous when it comes to political balance. But its point of reference is a media and political system heavily slanted towards economic elites and conservative ideas. Take the EU referendum debate. Research by Cardiff University found that the two sides of the official campaign were evenly represented in TV news.

But overall the voices of the right dominated, with the Conservatives and Ukip making up almost 80% of political sources. Loughborough University’s research produced similar findings, while the Cardiff researchers found that statistical claims made by campaigners were challenged in fewer than one in five cases. Post-truth politics is not, it seems, solely the preserve of the tabloid newspapers and the populist right.

Not only do government and Westminster sources dominate the BBC’s news output with a slant towards the right, the research shows, but the rightwing press has an agenda-setting function that influences the BBC’s output, favouring conservative interests. The corporation’s economic reporting has also reflected a narrow set of economic policies with even mainstream macroeconomic theory, let alone alternative or radical ideas, largely ignored.

Despite this evidence, for decades now the left has adopted a defensive posture on the BBC, with little serious discussion as to how it might be changed for the better. This partly reflects a concern over providing ammunition to the enemies of public service broadcasting.

Though claims about bias have been present throughout the corporation’s 90-year history, up until Margaret Thatcher the BBC was itself widely recognised as a small-c conservative organisation, closely connected to the state and the broader establishment. The major debates were on democratising the BBC and opening up its programme-making to a broader range of voices. The 1980s brought a shift, with vociferous complaints of leftwing bias. None of this changed much under New Labour, which broadly accepted the terms of the neoliberal settlement, courted the conservative press and was belligerent towards the BBC, especially over Iraq.

Over the same period, the politics and culture of the BBC itself were transformed. In the wake of Thatcherism, under the leadership of its director general John Birt especially, editorial authority was centralised, programme-making was marketised and the BBC’s reporting became much more pro-business. The overall result was that the BBC became less independent of governments and big business, and even less favourable to workers and their representatives, to social movements, and to political opinion falling outside the Westminster consensus.

This was the situation when the Conservatives returned to power, first in coalition and then with an outright majority, leading to renewed fears about the BBC’s future.

The real threat to the BBC has never been a sudden liquidation, but rather the erosion of the values it claims to uphold

The current royal charter expires on 31 December and the latest renewal process was a tense period for friends of the BBC. Initially, horror stories abounded: would Britain lose a cherished cultural institution and a much-valued bulwark against the crass commercialism and unabashed propagandising of the private news media?

The truth is that the real threat to the BBC has never been from a sudden liquidation, but rather the gradual erosion of the values it claims to uphold. When it comes to independence, always something of a myth given the power governments wield over the BBC on funding, appointments and the charter itself, there are serious concerns over the planned “unitary board” that will for the first time involve government appointees in the day-to-day running.

Much less remarked upon though has been director general Tony Hall’s proposal of a “competition revolution” intended to fully integrate the BBC’s in-house production (news journalism excepted) into the market. Hall’s “revolutionary” proposal, said to be driven behind the scenes at the BBC by the former Blairite MP James Purnell, was adopted in an even more radical form in the government’s white paper, and its implementation will accelerate a programme of market reform at the BBC that began in the 1980s.

But since the 1980s, the broadcaster has been defended by liberals and the left as an exemplar of public service ideals in a society increasingly dominated by corporate interests and commercial values. Not only is this not true, it does the BBC no favours. With the medium-term future of the corporation now secure, it is time for those of us who take the values of public and democratic media seriously to advance a realistic critique of the BBC and an ambitious programme of reform. This might mean saving the BBC from itself, not just from Rupert Murdoch.

Tom Mills is a lecturer in sociology at Aston University. He is the author of The BBC: Myth of a Public Service