BBC Trust urges viewers to have their say on BBC3: "We are not here to rubber stamp the proposals"

Roscoe also assured fans of BBC3 that the Trust, which regulates the BBC executive, was not there to automatically “rubber stamp” the BBC's proposal to move the channel online.

Speaking as the Trust formally launched a Public Value Test inviting submissions from viewers and other interested parties over the proposed closure, she said: “I have done a number of these assessments and this is not a fait-accompli. The purpose of this assessment is not to rubber stamp the executive’s proposals… Radio Times readers need to know about this and they need to get in touch with us.

“We want young people to know this is happening. This is their service. They need to know about the changes. And we are absolutely committed to understanding what those changes mean for our audiences and for that to inform our decision.”

Roscoe added that the BBC Trust would be prepared to reject the proposals despite the detail and effort that has gone into the BBC executive’s closure plans, pointing out that the last time the Trust undertook a Public Value Test to examine a major BBC policy change in 2008 it rejected the BBC's proposals.

“There was an awful lot of fanfare when the executive first started talking about local video," said Roscoe. "What they essentially wanted to do was expand their footprint of local video journalists to mimic broadly that of local radio stations. And a lot of people in the media and industry stakeholders broadly assumed that this would be a fait-accompli, that this would be rubber-stamped. But the Trust turned these proposals down.

“The Trust approaches this with an open mind. That is what we are here to do.”

Roscoe also said that it was “in the gift of the Trust” to amend some of the BBC executive’s proposals over BBC3 and change some elements.

However she would not be drawn on the surprise announcement that independent producers Hat Trick and Avalon want to buy BBC3 for £100m, and declined to comment on whether this would be allowed under the existing terms of the BBC's charter.

Currently the BBC executive wants to close BBC3 as a broadcast channel and plough the savings into other areas of the Corporation, with an extra £30m going to TV drama.

The online BBC3 would follow the maxims “Make me laugh” and “Make me think” by focusing on comedy and serious factual programmes when it ceased as a broadcast channel.

The BBC has said BBC3 would be "reinvented as a new and innovative online service".