King Charles reportedly offered Prince Harry the use of a royal residence on his trip to the UK last week

However, Harry is thought to have ultimately opted for three nights in a hotel.

Friends of the king insisted Harry hadn't asked to see his dad or invited him to the Invictus thanksgiving service at St. Paul's Cathedral, but those close to Harry insisted the request to see his Charles was made well in advance of the trip, which had been "long on the radar", and pointed out he is required to give 28 days notice to the king and the Home Office to request security when he is in the UK.

A source told the outlet: "It's all very sad. While it is true that the King is understandably wary about meeting with Harry, given the publicity circus that seems to surround all such visits, he did of course agree to see his son at the most vulnerable moment of his illness [in February], and at very short notice.

"While he was hardly going to roll out the red carpet the moment this Invictus trip was announced, with doctors advising him to focus on his treatment and recovery, the idea that he refused to find space in his diary ... well, let's say recollections may vary once again."

However, a friend of Harry's said: "I can't imagine that request [from Harry to Charles] fell through the gaps. Even if they didn't get a request, which I don't believe, could His Majesty not have made a request to see his son? It was widely known he was coming."

The duke's representative previously claimed Charles - who is still receiving cancer treatment - was too busy to see his son.

He said in a statement: "In response to the many inquiries and continued speculation on whether or not the Duke will meet with his father while in the UK this week, it, unfortunately, will not be possible due to His Majesty's full programme.

"The Duke of course is understanding of his father's diary of commitments and various other priorities and hopes to see him soon."