Broadcaster Andrew Neil has paid tribute to the BBC after announcing he will be leaving after 25 years.
The 71-year-old journalist is to become chairman of new TV channel GB News, which is due to launch early next year.
He said he was leaving the BBC, where he has presented shows such as Daily Politics and helped front its election coverage, with a "heavy heart".
The BBC said he had "informed and entertained millions of viewers" over the years.
Neil's last appearance for the BBC will be in early November when he will help lead its coverage of the US presidential election.
The former Sunday Times editor has been at the heart of the BBC's political coverage for the best part of three decades.
As well as presenting Daily Politics and its successor Politics Live, he was the host of the popular late-night discussion show This Week for many years.
His penetrating and often combative general election interviews with party leaders won him wide critical acclaim.
He was involved in a row with Downing Street prior to last year's election when he publicly challenged Boris Johnson on air to appear on his show, saying his absence from the screens represented a "question of trust".
The PM was the only one of the main party leaders not to be questioned by Neil.
Earlier this year, the BBC said the weekly Andrew Neil Interview show, which had been broadcast since 2019, would not be recommissioned but it was in discussion with him about other formats.
They were/are the best of the best. If they can make me look good, they can make anybody look good. There could have been a different outcome but for reasons too dull to adumbrate, we’ll leave it there. I wish the BBC and the new DG well. The BBC will always be special to me.— Andrew Neil (@afneil) September 25, 2020
Announcing his departure, Neil said these discussions had not come to fruition and he had decided to take the role of chair of GB News, where he will also host a daily show.
"With heavy heart I announce I will be leaving the BBC," he wrote on Twitter.
"Despite sterling efforts by new DG (director general) to come up with other programming opportunities, it could not quite repair damage done when Andrew Neil Show cancelled early summer."
He thanked everyone who had helped him during his time at the BBC, describing them as the "best of the best" and saying the corporation "will always be special to me".
In a statement, the BBC said it would like to give its "heartfelt thanks" to Neil, describing him as a "formidable and talented broadcaster".
"For years, he was at the heart of the irreverent and much-loved This Week and played a key role in the Daily and Sunday Politics, Politics Live and the BBC's general election coverage," it said.
"We are sorry the US election coverage will be his last BBC presentation for the foreseeable future but he will always be welcome at the BBC."
GB News is a new 24-hour news channel which will compete with the BBC, ITV and Sky News. Its financial backers include the US media giant Discovery.
The BBC's media editor Amol Rajan said its launch and Neil's signing was a "big moment for British culture".