The King now has a 'warmth' towards Prince Harry and Meghan Markle – but the duke's relationship with William will never improve, a royal author close to the Sussexes claimed today.

Omid Scobie, the journalist once dubbed the couple's 'cheerleader', said 'things have moved forward' with Harry's father and the 'iciness has thawed out', but added that 'I don't see it will ever change' with the Prince of Wales.

Speaking in a new ABC News Studios documentary about Harry and Meghan's return to Britain, he also addressed whether Kate was a 'peacekeeper' who could help heal the rift.

In an exclusive clip from 'Harry & Meghan: The Return of the Prince', Mr Scobie said: 'I think we've seen with Charles things have moved forward and that iciness has thawed out. There's a warmth there. With William, I don't see it will ever change.

'There's always this talk of Kate potentially being the peacekeeper, the one that could bring the two brothers together. If I've learned anything over the years from covering them, it's that Kate has very little to do with that relationship between the brothers.'

The programme – part of the 'Impact x Nightline' series – also heard from Erin Hill, senior editor at People magazine which has a close relationship with the Sussexes.

Ms Hill said: 'Palace insiders have told People that William and Kate behind the scenes have decided to take a very old-school royal approach to this.'

She labelled this as 'keep calm, carry on, do the job', adding: 'So right now, Harry and Meghan, they're not a priority for them, and they're very much looking to the future.'

The documentary heard from royal commentators, experts and reporters to discuss the ramifications of Harry and Meghan's return to the UK after six years in the US.

They talked about the public falling out with the Royal Family and whether there will be reconciliation as the 30th anniversary of Princess Diana's death approaches.

Others involved in the programme were royal experts Robert Jobson, Victoria Murphy, Alastair Bruce, Elizabeth Holmes, Kinsey Schofield and Afua Hagan.

Farzana Baduel, co-host of BBC Radio 4's 'When It Hits the Fan,' also appeared – as did Maggie Rulli, the ABC News journalist who interviewed Earl Spencer last week.

The Sussexes arrived in the UK on August 26, making their dramatic U-turn after quitting the working monarchy and heading to California in 2020.

They stepped down as working royals for personal and financial reasons but rumours remain rife as to why they unexpectedly relocated. 

Speculation ranges from the couple wanting their children to develop a closer relationship with their grandfather the King, Meghan seeking a return to acting and the Sussexes wanting to increase their profile.

Meghan's friend Kelly McKee Zajfen said this week that the duchess has received a 'loving' reception after returning to the UK, which has been 'beautiful to witness'. 

In the run-up to their return Charles was said to be glad to be able to spend more time with the Sussex family, but remained adamant they would not be working royals, and there was no half-in, half-out option.

The move has not been plain sailing, with Harry and Meghan pulling their children Prince Archie and Lili out of their new school after just two days when heavy traffic in the area meant their private security team struggled to stay in a convoy during the school run. The youngsters have now transferred to a new school.

Tensions also grew between Team Sussex and the Royal Household when a letter, authorised by the King, was circulated to senior stakeholders in the Government reiterating the couple were 'private citizens' and setting out guidance on how they should be treated.

Harry and Meghan were said to have been caught off guard by the instructions, with the couple, who are waiting to hear whether they will be given taxpayer-funded security, reported to prefer the term 'public figures' instead.

Meanwhile the serialisation of a book about Diana written by Earl Spencer has made serious allegations against the King.

The earl accused the monarch of gaslighting him after Buckingham Palace pushed back against allegations that Charles said 'we'll forget her soon enough' after Diana died.

This prompted a war of words between the earl and Buckingham Palace, which said in a responding statement that 'the pain of fraternal grief can cloud reason'.

Neither Harry nor his brother Prince William have commented on the book – serialised by the Daily Mail – although they were both told in advance that it was being released. 

Separately, it was reported on Monday that Harry is in talks to make a documentary about his mother to mark the 30th anniversary of her death.

The duke is understood to have asked a number of Diana's friends and relatives if they would take part in a commemorative film ahead of the milestone in August next year – but the project has not been confirmed at this stage.

Harry was in New York City earlier this week carrying out a series of engagements – including a speech about AI at the Clinton Global Initiative annual meeting on Wednesday.

He also appeared at a National Geographic and De Beers Okavango Eternal event at the Jardin de Sur Madison; a Diana Award and Service Now discussion on the future of work, young people and AI at Goals House NYC.

Further events include an event for Harry's sustainable travel initiative Travalyst; and a keynote speech at the Skift Global Travel Forum.

The trip to the US came after he carried out three engagements in the UK – his first since returning to Britain.

The duke attended the Invictus Spirit Awards in London last Thursday to honour members of the Invictus community at his first event since returning to the UK.

He went to Ninestiles Academy in Birmingham the following day to launch Inspire, a new education programme linked to the Invictus Games in the city next June.

Harry then returned to London on Monday for the WellChild Awards to celebrate the achievements and resilience of seriously ill youngsters and their families.

But Meghan has not joined him at any events so far – and the last public engagement they attended together was a David Foster Foundation gala in Canada on August 7.

'Harry & Meghan: The Return of the Prince' is streaming on Disney+ and Hulu