A grassroots campaign to preserve the BBC is to launch on Monday outside New Broadcasting House, ahead of a week in which the corporation’s director-general, Tony Hall, and the chair of its board, David Clementi, are both to appear as witnesses in front of MPs to defend the current funding model.

The “It’s Our BBC” movement has been prompted by signs the government intends to alter the status quo, forcing the corporation to strip back its services and adopt a subscription model of the kind used by streaming services such as Netflix.

Conservative MP Julian Knight, who will chair Thursday’s meeting of the digital, culture, media and sport select committee, has already spoken of his belief that the most important principle will be to maintain public access to high-quality broadcast services, rather than to prioritise the BBC as the only source.

The newly appointed secretary of state for culture, Oliver Dowden, has also echoed comments made by his predecessor, Nicky Morgan, who suggested last month that the time had come to reassess both the funding and the purpose of the BBC. Speaking last week at a telecoms conference, Dowden said: “The BBC needs to be closer to, and understand the perspectives of, the whole of the UK and avoid providing a narrow urban outlook.”

To draw attention to government plans to “whack the BBC”, as reportedly outlined by Dominic Cummings, the prime minister’s adviser, activists will on Monday stage a game of “Cummings Whack-a-Mole” outside the corporation’s London HQ.

“If Dominic Cummings gets his way, we’ll be left with little more than a Fox News-style broadcast media. That would be an unmitigated disaster for our media, for our democracy and for our country,” said Cat Hobbs, director of We Own It, the public ownership campaign group that is co-ordinating the new BBC support drive. Organisers will be inviting members of the public to dress as Cummings and take part in a giant, symbolic game of whack-a-mole, in which they will be able to “whack” a number of well-known BBC programmes, such as Planet Earth and EastEnders, with a five-foot-long mallet.

Facebook Twitter Pinterest Culture secretary Oliver Dowden said the time had come to reassess the funding and purpose of the BBC. Photograph: Stefan Rousseau/PA

The campaign’s opening publicity stunt is designed to mark the release of a national petition calling for a publicly owned, fair and sustainably funded future for the BBC. It will be followed on 16 March by the launch of a “People’s Consultation”.

The challenge to the basis of the BBC’s future comes on top of 30% cuts to its public funding level since 2010. And earlier this year 450 job losses in the news division were announced as part of streamlining budget cuts. The government’s consultation into decriminalising evasion of the BBC’s licence fee, a move supported by Knight, continues.

“The BBC is a national treasure,” said Hobbs this weekend. “Its programmes and services have had an unparalleled impact on our culture and understanding of the world – from Planet Earth to The Archers, Match of the Day to the World Service. As the UK forges a new path after Brexit, we should be proud of our fantastic, globally respected British institutions like the BBC. It is utterly staggering that the government would want to strip that back and leave us without the wonderful contribution the BBC makes.”

The petition is also to call for the broadcaster to continue to make programmes aimed at every listener and viewer and for the government to once again pay for TV licences for over-75s.

The campaigners aim to gather support for a new and independent board, with a citizens panel, that would be able to cap excessive staff pay and build stronger regional journalism.

“We know the BBC isn’t perfect. But the way to solve that isn’t with aggressive grandstanding, or with threats to undermine the BBC’s future and reduce its funding,” said Hobbs. “It’s to secure its funding for the long term, and to make sure the BBC takes action to reform for the better – capping excess pays and ramping up its regional reporting.”