In a section detailing how he walked with his grandsons behind their mother’s coffin, his biographer Gyles Brandreth said, contrary to popular opinion, it was not his idea. 

Prince Harry has previously said “no child should be asked to do that”, while Prince William said: “It wasn’t an easy decision and it was a sort of collective family decision to do that… there is that balance between duty and family and that’s what we had to do.” 

In the new programme, Mr Palmer says of the Duke: “He’s come in for criticism for that but it was not his choice, not his idea. And there’s a moment where they go under the Horseguards Parade arch where it’s quite clear that Prince Philip – and I asked him about this he said, ‘Yes, I didn’t think the cameras could see us’ – at that point he turns to William and comforts him. 

“You’ve just got to watch that moment and realise here is a grandfather who is trying to help his young, very vulnerable grandson struggle through this awful awful moment. 

“He knew what it was like to be a member of a dysfunctional family and he did his damnedest to make sure that did not happen to his grandchildren.” 

Brandreth, the writer and broadcaster, added: “It wasn’t his idea but there was a tradition in the Royal family of walking behind the hearse. 

“There was no plan originally for Prince Philip to be part of that. Prince Philip said to Prince William, ‘If it would help I can walk alongside you.’ So far from being what was reported, it was an act of grandfatherly kindness.” 

Philip: Prince, Husband, Father will be broadcast on Tuesday, Dec 21 at 9pm on ITV.