A group of 128 British authors, actors, editors and filmmakers have warned that “political and financial attacks” threaten the future of the BBC and other UK public service broadcasters. In an open letter published Wednesday, the group -— which includes writers Salman Rushdie, Hilary Mantel and Armando Iannucci, and actors Hugh Grant and Adrian Lester — claim that a secret panel with no public record of meetings is advising Prime Minister Boris Johnson’s government on the future of the BBC. Published by the British Broadcasting Challenge, a campaign group, the letter says that Britain’s “unique” tradition of independent publicly-funded broadcasters has promoted quality, diversity and innovation, created space for talent, and “underpins the ways in which we as individuals, as nations and regions, relate to each other and to the world. Its independence from government and its commitment to impartiality serve everyone.” The letter, which is also signed by former Financial Times editor Lionel Barber, former Guardian editor Alan Rusbridger, and Oscar-winning film producer Simon Chinn, goes on to warn that these public service principles are “under severe threat,” from streaming services, big tech companies and the government. CNN Business has reached out to the UK government for comment. The public show of support by prominent cultural figures comes as the BBC confronts unprecedented political hostility, looming threats to its funding, deep cuts to some services and increasing competition from digital platforms ahead of its centenary in 2022. “BBC funding has been cut by 30% over the past 10 years … and faces more cuts in the next funding settlement,” according to the letter, which said that successive cuts have diminished local and regional broadcasting at the “very moment when more investment is needed to support local democracy and accountability.” The public service broadcaster’s primary source of revenue — annual fees every household must pay for watching live TV on any channel or platform — is under constant threat of being cut or scrapped by the government. “It’s clear that the BBC TV license fee has a limited shelf life in a digital media landscape,” Julian Knight, the chair of a parliamentary committee reviewing public service broadcasting, said in a report published last month. Though the UK media scene is defined in part by a freewheeling and often partisan tabloid press, its TV news channels largely frame their coverage down the middle, with broadcasters such as the BBC and ITV maintaining high levels of public trust. A big factor in this is media regulator Ofcom, which enforces rules on impartiality and accuracy for all news broadcasters. Those who breach the rules can be censured or fined — putting pressure on TV channels to play stories fairly straight. That system could face a new challenge soon. GB News, an upstart competitor to the BBC, is expected to launch in the coming weeks. The 24-hour news channel is expected to feature a greater number of opinionated commentators, which could challenge Ofcom’s requirement of “due impartiality” in news reports. Signatories to the letter argue that the “soft power” of UK public broadcasters, including the BBC World Service, is a “significant national asset” and particularly important in a “post-Brexit, post-Covid world order.” “We believe that this is the moment — in an era of misinformation and the ‘weaponised’ politicization of news and opinion — to build up our Great British public service broadcasters rather than diminish them,” the letter stated. — Julia Horowitz and Hadas Gold contributed reporting.