Thomas Markle has told how he believes daughter Meghan and Prince Harry should have returned to Britain to help the Queen during the coronavirus crisis rather than move to LA.
The 75-year-old has been left disappointed by the revelation the couple have permanently moved to Los Angeles with his grandson Archie - and they now live just 155 miles from him.
Mr Markle is still hoping they will reverse their decision to give up their roles as full-time royals.
In an exclusive interview, Thomas told the Sunday Mirror: "I think Meghan and Harry should go back to the Royal family in the UK and be supportive of the Queen.
"I think they should be in England at this time and not in LA."
He added: "I really support the idea of them going back to the royal family.
"They can join the A-list and make lots of money, of course, when the problem with the virus is over.
"But they will never find the respect they would have as full members of the royal family."
The retired Hollywood lighting director sent his best wishes to both the Queen and Prince Charles, who is in self-isolation after contracting Covid-19.
He revealed Meghan has still not contacted him, despite him being at high-risk of the virus due to his heart condition.
He again begged her and Harry for forgiveness and said he hopes the pandemic will remind them what is important in life.
And he admitted he is worried Meghan could now be struck down by the virus, which is raging in California, where she and Harry set up in their new home earlier this month, just days before President Trump implemented a travel ban.
Thomas said: "I am in the high risk category, but now a number of young people are also coming down with it.
"If I could say anything to Harry and Meghan right now it is that life is too short.
"I would certainly tell them to be careful and I would tell them that I love them.
"This is the time to think about what is really important in life - it's too short and unpredictable.
"While we have to isolate physically, there is no reason to isolate personally from each other at this time."
Thomas is at high-risk of contracting coronavirus due to his age and a string of underlying health conditions, including a heart problem, hypertension and prediabetes.
He hasn't spoken to Meghan since he missed her wedding to Harry after suffering a heart attack in May 2018.
They fell out shortly before the ceremony after it emerged he had collaborated with a paparazzi photographer to make money from staged photos.
And he has yet to meet his son-in-law or grandson Archie, 10 months.
Thomas is desperately hoping Harry, 35, will see anyone can make a mistake after he was duped by Russian pranksters impersonating eco-activist Greta Thunburg and her dad Svante.
The Prince was duped in two phone calls with notorious jokers Vladimir Kuznetsov and Alexey Stolyarov, during which he indiscreetly told them he is "completely separate" from most of the Royal Family and spoke openly about his agony over "Megxit".
He also opened up to the fake Greta about the tension at the heart of the Royal Family and was also critical of US president Donald Trump.
Mr Markle said: "We all think we do something right and it turns out to be wrong.
"Harry recently made a huge mistake talking to those Russian pranksters.
"He got tricked by those pranksters and I got tricked by doing those photos.
"We all make mistakes and I made a huge mistake.
"I should forgive them and they should forgive me.
"Ultimately, maybe it's time for Archie to say hello to grandpa."
Thomas lives alone in Rosarito, Mexico, just over the border from California, which is now in Covid-19 lockdown.
He has been suffering from a cold for the last two months, but insists it is not coronavirus.PRINCE CHARLES SEEN FOR THE FIRST TIME SINCE CORONAVIRUS DIAGNOSIS
He is now preparing to go into self-isolation in Mexico.
He said: "I have a good supply of food in, I'm ready to self-isolate and stay at home. I have more than enough food and water."
Thomas is now preparing to be a witness in the legal battle over a letter Meghan wrote to him detailing her heartbreak at their rift.
He originally kept silent about Meghan's five-page note posted to his home.
But six months later its existence was revealed in a US magazine, anonymously quoting fivefriends of Meghan.
Thomas felt the nameless pals attacked him and misrepresented the letter, prompting him to take it to a UK newspaper.
He has now agreed to testify at London's High Court. But he is now hoping it will not come to that.
And he is now being comforted by Meghan's half-siblings Tom Jnr, 53, and Samantha, 55, who are in daily contact with him.
He said: "Every day I hear from Tom and Samantha, they call.
"They're both doing fine at the moment."