GB News has secured £60m of fresh investment as part of an ownership shake-up in which the Hollywood titan Warner Bros. Discovery has sold its stake in the fledgling news network.

Sir Paul Marshall and Dubai investment firm The Legatum Group have bought out the US entertainment giant and GB News co-founders Andrew Cole and Mark Schneider.

The departure of high-profile backers just over a year since GB News launched is the latest upheaval to strike the opinionated news station, which endured a rocky start caused by technical problems, an advertising boycott and the departure of key talent, including chairman and lead presenter Andrew Neil.

However, the cash-injection from two of its existing shareholders will embolden the broadcaster's attempts to amass an audience big enough to turn a profit and become a credible challenger to the BBC's 24-hour rolling news channel.

Chairman Alan McCormick, a partner at Legatum, said the investment was “testament to our confidence in the momentum and trajectory of GB News after a very strong first year”.

“Our additional investment means the channel will embark on robust and exciting plans for the next stage of its growth and development.”

The £60m fundraising, which is poised to be completed in the coming weeks, comes as GB News attempts to stiffen its challenge to the BBC and Sky News by splashing cash on its presenting line-up.

Camilla Tominey, the associate editor of The Telegraph, and the Daily Mail's Andrew Pierce have been poached from Global's talk radio station LBC. Ms Tominey will become a political presenter, while Mr Pierce will launch his own show later this year.

Michael Portillo, the former Conservative cabinet minister, is also joining from Rupert Murdoch's Times Radio to support GB News' political coverage and present a new programme in the autumn.

GB News had outmuscled Mr Murdoch's TalkTV in a bidding war to secure a more prominent channel slot on Virgin Media.

It is about to move this month from channel 626 to the more prominent 604 slot on the pay TV operator's channel guide, according to Virgin Media's website.

On the new fundraise, Angelos Frangopoulos, the chief executive of GB News, said: “We’ve already employed more than 200 journalists and now we’ll invest more deeply in a number of areas, including a new digital product suite, our technology and studio, subtitles, additional distribution platforms, and exciting new talent.”

All Perspectives, the owner of GB News, has been bankrolling the broadcaster's expansion with £46.5m worth of cash since Spring last year.

GB News has slowly grown an audience to challenge Sky News, while fighting off a challenge from TalkTV that has struggled for viewers.

TalkTV's The News Desk with Tom Newton Dunn and Piers Morgan Uncensored attracted average audiences of 2,500 and 33,900 in the 7pm and 8pm slots on July 28.

GB News' 7pm show presented by the former UKIP leader Nigel Farage secured 64,000 viewers, while its 8pm show attracted 46,000 viewers. BBC News brought in an audience of 72,000 and 58,000 across the 7pm and 8pm slots.

GB News secured an average audience of 81,300 in the evening prime time slots this week, with Sky News attracting 66,100 over the same period, according to the TV ratings compiler BARB.

In a statement, Warner Bros. Discovery said it sold its stake in GB News after evaluating the group's investments in a string of news brands following the merger of Discovery and WarnerMedia earlier this year.

The owner of CNN Worldwide said GB News had built a “growing and loyal audience” in its first year and brought “another voice to British broadcasting”.