Campaigners against proposals to turn digital station BBC Three into an online-only channel in the autumn have delivered a petition, signed by more than 270,000 people, to the BBC Trust.
The channel, which brought us Gavin and Stacey and Little Britain, is under threat due to cost-cutting at the BBC.
Labour MP John McDonnell said they hoped the petition would "send a message to the top" to "think again".
BBC bosses plan to shift the savings to other areas, earmarking £30m for drama.
The Trust, which has to approve the proposals from director general Tony Hall and the BBC executive, is currently carrying out a "public value test" (PVT).
"Only last month the BBC Trust claimed that they want to give power to the people rather than leaving important decisions within the hands of a 'small elite' management at the BBC," said Jono Read, who set up the original petition online.
"If they genuinely mean this they will listen to the 270,000 people who have signed the Change.org petition against the closure of BBC Three, and the views of key BBC Three talent who are dead set against the proposals."
'Save BBC Three'
Mr McDonnell, who tabled an Early Day Motion (EDM) opposing the closure, told Radio Times outside the BBC's New Broadcasting House in London: "This is an extremely popular channel, it is extremely innovative. The BBC is cutting off its nose to spite its face with this proposal."
He added: "The BBC has never closed down a channel before and we are asking them to think again. The BBC is growing the future audience with BBC Three and the thinking seems so short-term.
"This sends a message to the top. The leadership of the BBC cannot ignore this."
Protest singer One Man and his Beard - AKA Manchester musician David Gorton - also joined the group of campaigners to perform a song he has written called Save BBC Three outside New Broadcasting House.
After the protest they marched the short distance to the BBC's Trust headquarters to hand the petition to Jon Cowdock, the Trust's head of business strategy.
He revealed more than 20,000 people had submitted their comments to the consultation so far and "it is not a fait-accompli."
"We will take a view based on the evidence. People who have signed this have not wasted their time. This is an important contribution," said Mr Cowdock.
'No easy solution'
A statement from the executive said: "With the licence fee frozen we've had to make some difficult choices in order to save £800m a year, including moving BBC Three online.
"There is no easy solution and we have chosen to make a bold move to reinvent the service rather than simply having to take money out of all our programmes across the board."
Last month, BBC bosses ruled out selling the station to a group of independent TV producers who stepped forward to try to keep it on TV and increase the budget.
Leading production companies Hat Trick and Avalon, the makers of shows such as Have I Got News For You and Not Going Out, said they would triple the investment being proposed by the BBC if it moves online to BBC iPlayer.
But the BBC said: "BBC Three is not for sale because it's not closing."
The Trust said it would "carefully consider all contributions made to the consultation... before reaching any conclusions".