Dominic Cummings’s thinktank called for the “end of the BBC in its current form” and suggested rightwingers should work to undermine the credibility of the broadcaster, branding it the “mortal enemy” of the Conservative party.

Cummings, who is Boris Johnson’s most powerful adviser, was the director of the New Frontiers Foundation when it called in 2004 for a campaign to target the BBC and the creation of a Fox News equivalent that would not be constrained by impartiality rules.

Opposition MPs said on Tuesday that the views of Cummings’s thinktank would fuel suspicions that Johnson’s administration is gearing up to overhaul the BBC.

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The disclosure comes at a sensitive time for the corporation, whose director general. Tony Hall, announced on Monday he was standing down. Several Tories have since called for an end to the licence fee, while Labour figures have warned that the BBC is facing a dangerous moment as it approaches its 100th anniversary.

The thinktank also suggested an end to the ban on TV political advertising to allow politicians to speak directly to the public in ad breaks during Coronation Street, for example, and the “development of the web networks scrutinising the BBC and providing information to commercial rivals with an interest in undermining the BBC’s credibility”.

One post from September 2004 said: “There are three structural things that the right needs to happen in terms of communications... 1) the undermining of the BBC’s credibility; 2) the creation of a Fox News equivalent / talk radio shows / bloggers etc to shift the centre of gravity; 3) the end of the ban on TV political advertising.”

Another idea proposed was that government ministers should avoid appearing on BBC Radio 4’s Today programme – a policy that has come to pass since Cummings entered Downing Street as Boris Johnson’s de facto chief of staff last year.

The suggestions were made in a series of long blogposts in 2004 and 2005 by the New Frontiers Foundation, which was a short-lived free market thinktank that aimed to emulate rightwing US organisations such as the Heritage Foundation. Cummings was the director of the thinktank and described as one of two “principal staff”. It folded due to lack of support.

No 10 declined to comment but a Whitehall source said it was “not particularly uncommon for special advisers to have expressed opinions before entering No 10”.

There are signs that Johnson’s government is already looking at changing the BBC’s funding model, including the possibility of decriminalising non-payment of the licence fee as a first step.

The prime minister first called the licence fee into question during the election campaign and Nicky Morgan, the culture secretary, has suggested a move to a Netflix-style subscription system could be considered for the BBC, potentially ending almost a century of public broadcasting funded by a licence fee.

Ben Bradshaw, the Labour MP and former culture secretary, said Cummings and some Tory MPs “would like nothing more than to replace the BBC with a rightwing propaganda channel like Fox”.

He added: “The BBC belongs to the British public, not the government, and the public value the public service ethos of the BBC, objective and accurate information and news and the broad range of much-loved radio and TV programmes and would not take kindly to them being sacrificed to Rupert Murdoch.”

Ed Davey, the acting leader of the Liberal Democrats, said: “The BBC is a national treasure and if Dominic Cummings thinks he has got a mandate to go after Strictly and David Attenborough he has got another thing coming.

“Every politician and party will have their problems and frustrations with the BBC, but often that’s because the Beeb are doing their job. The Liberal Democrats will fight for the BBC tooth and nail.”

Facebook Twitter Pinterest A sign at a pro-Brexit protest in London last May. Photograph: Avpics/Alamy

Cummings has criticised the BBC in personal blog posts since 2013, accusing it of showing pro-remain bias, but his thinktank’s proposals from a decade earlier went much further, calling for a campaign to target the corporation and transform the broadcasting landscape to make it more favourable for rightwingers.

In a post offering advice to the Tories, the thinktank said the party should copy the US Republicans by realising they were in a “culture war” in which they needed to “shape the culture actively in their favour over long periods with large efforts”.

In November 2004 Cummings wrote an article for the Business, a now defunct newspaper, calling for a “campaign to end the licence fee and break the BBC’s stranglehold” and for people to “hire lawyers and investigate whether the ban on television political advertising can be overturned in the courts”.

The same argument was made multiple times by the New Frontiers Foundation throughout 2004. The thinktank suggested the Conservatives “can only prosper in the long-term by undermining the BBC’s reputation for impartiality in the way CBS’s reputation is being undermined now, and by changing the law on political advertising.”

It added: “The BBC is a determined propagandist with a coherent ideology. We are paying for it. We should not be. We should be changing the game.”

Another post from July 2004 said the right “should be aiming for the end of the BBC in its current form and the legalisation of TV political advertising”. Another argued that the “privileged closed world of the BBC needs to be turned upside down and its very existence should be the subject of a very intense and well-funded campaign that involves bringing out whistleblowers armed with internal memos and taped conversations of meetings”.

The New Frontiers posts advocated a number of ideas that Cummings has since promoted while in government office. These include the creation of a US-style research body to fund high-risk scientific projects, and reform of Whitehall.

One of the thinktank’s blogposts said: “A serious Conservative government would thoroughly purge the civil service and remove swathes of the top people. Rather than pretend that they are neutral, it would be healthier for Britain to adopt the American system and have routine purges as different political parties gain democratic power.”

The thinktank also made the argument that appearing on the Today programme was not helpful to ministers. “It is a mistake in general for a Conservative leader to appear on the Today programme unless he is announcing a major new positive proposal, especially if it is to answer a series of attacking questions about ‘strategy’. Today exists to try to make him look stupid and create an echo of ‘U-turn’ / ‘gaffe’ / ‘confusion’ stories, as with other major politicians. Effort should be diverted from Today to programmes that affect the public far more,” it said.

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Johnson’s ministers have been banned from appearing on Today since after the election in December.

Other ideas floated by the thinktank included research into “hypersonic bombers”, reducing trade tariffs “to zero, thus bringing cheaper goods for us and profits rather than disaster for the developing world”, reform of the United Nations and a closer alliance with the US.

This was to involve creating with America a “different kind of networked global alliance based on free trade (not a customs union and single market harmonisation), mutual defence, and systems administrator units capable of peacekeeping and disaster relief”.