Hugo Vickers, author of a number of books about the royals, said that Harry had “thrown in his lot with his wife” and “slagging off his family” had helped nothing. The tension looks likely to over-shadow the un--veiling of the Princess Diana statue at Kensington Palace on Thursday. While TV -cameras will be there, no -programmes about the unveiling are planned. Mr Vickers said: “The story will not be the actual unveiling of the statue but of the two boys together, that’s what every--one will be focusing on.”

       Any attempt at reconciliation in London could see Harry having to answer for it when he returns to his wife in Los Angeles, warns Mr Vickers.

       On the chances of making peace, the author said: “I don’t know what they can do under the present circumstances. Harry has got to wake up to what’s going on. It’s a very unpleasant situation and I don’t think it’s going to be the right moment this week.

       “Harry is so under the thumb of Meghan it is not really possible until he emerges from that.”

       He added the brothers could communicate by videolink or phone but said neither Harry nor Meghan wanted to. He said: “He has thrown in his lot with his wife. That’s it, isn’t it? Slagging off his family didn’t help anybody. It’s a dreadful situation.”

       Mr Vickers, who also believes Prince Charles will not intervene in the matter, added: “You’ve got to remember that Harry has to return to his wife in Los Angeles.

       “If he starts reconciling, he will get his head bitten off, won’t he?”

       Royal author and commentator Richard Fitzwilliams agreed that a cooling-off between the princes “doesn’t look hopeful”. He said: “I think they will appear publicly mutually supportive.

       “But with Harry’s recent interviews and with so many rumours circulating, things need to become a lot calmer.”

       It comes as royal author Robert Lacey claimed that though the princes were seen chatting amicably following Prince Philip’s funeral in April, once they were behind closed doors they

       were “at each other’s throats”.

       And Mr Lacey also claimed Meghan’s self-promotion and self-pity left William infuriated.

       A close friend of Harry’s reportedly admitted: “Meghan can be a 500 per cent nightmare. The never-ending PR. She’s just so... American!”

       There were also allegations that Meghan bullied royal staff and when it was pointed out to William that everyone has a -difficult sister-in-law, he is said to have responded angrily: “But look at the way that bloody woman treated my staff – merciless!”