Broadcaster Jonathan Dimbleby has hit out at the BBC's "enemies" and warned against more cuts to the licence fee.
The appointment of Tory MP John Whittingdale, who has called the licence fee "worse than the poll tax", to the post of Culture Secretary has led to speculation that the broadcaster could face major changes to the way it is funded.
But Dimbleby called on the Government to think twice before delivering a punitive licence fee settlement when it comes to charter renewal.
He told RadioTimes.com that "the nation would lose massively if the BBC were to face any kind of demise".
"I believe that while there are powerful vested interests who would like to see the BBC denied a licence fee, without a licence fee the BBC could not do what it does.
"It's stressed at the moment. There are cuts still coming," he said.
"And in some parts of the BBC's output, not least in radio ... and in television, those cuts are pretty close to the bone," the Any Questions? host said.
The broadcaster admitted that there are "things wrong with the BBC", saying that its "bureaucracy can still be slimmed" and that "there are too many individuals who are not doing much".
But he added: "There comes a point where that crossover between savings, proper savings and weakened programmes means that the BBC really is editorially diminished and weakened.
"And if you're not careful you get a vicious circle and people say 'it's not as good as it was, let's get rid of it'."
The son of the late broadcaster Richard Dimbleby and brother of Question Time presenter David added: "The BBC has enemies, it has powerful enemies. It has powerful enemies in the press and powerful enemies in Westminster - some for ideological reasons, some for straight commercial reasons."
Dimbleby, who is presenting The BBC At War, a BBC2 documentary series charting how the broadcaster became a lifeline of information during the conflict, insisted that the vast majority of people are happy to pay the fee, currently set at £145.50.
"I do not believe the licence fee is toxic ... The great majority are prepared to pay the licence fee and believe that at around 40p per day it's cheaper than chips," he said.
"The viewers are not anti. You can ask a silly question – 'do you want the licence fee to be cheaper?' - and they won't say they want to pay any more money.
"But ask whether they trust the BBC or want the BBC to continue and the answer is an overwhelming 'yes'."