According to a royal expert, the Queen and Prince Philip struck a deal on how to deal with the death of either.

Prince Philip died in April at the age of 99.

The queen and Prince Philip were constantly at one other’s sides throughout their 73-year marriage, whether in the tea rooms of Buckingham Palace or on far-flung trips to the Commonwealth.

When the Duke of Edinburgh died in April, the image of Her Majesty sitting alone and sad at his burial at Windsor Palace shattered hearts all across the country.

The Queen then entered a two-week mourning period for her husband.

But she has now resumed her public responsibilities with a big grin on her face.

The courageous turnaround, according to the Daily Mail, is due to a secret pact the pair made if one of them died: “whoever was left should mourn, but not for too long, then enjoy what remained of their life”

As Elizabeth returned to work after the Duke of Edinburgh’s death, a former top staffer at the palace told PEOPLE: “Her family will step up and be by her side, but she will carry on. She understands that she has a job to do, and [Philip] would have wanted her to crack on.

“She did do so when he retired from public life.”

Richard Kay, a friend of Princess Diana’s who complimented the Queen for “bantering” with Boris Johnson over then-Health Secretary Matt Hancock, said: “The subtext was clear: even if they weren’t, she certainly was.

“And her observation went a long way to show that she had emerged from her period of mourning and was ready to participate fully in the affairs of the kingdom.”

He wrote: “The smiles we saw in Cornwall have been replicated on every public appearance since. From that intimate, scaled-down Trooping the Colour ceremony at Windsor Castle to finally making it on to the racetrack for the last day of Royal Ascot.

“Her passion for horse racing is no secret but the success of the Queen’s breeding programme meant she had seven runners during Ascot Week and several winners elsewhere.

“‘It has all helped to perk her up no end,’ says a racing friend. ‘She misses Prince Philip dreadfully but she was prepared for his passing. Caring deeply for someone whose health is in decline is always exhausting and I am sure it was no different for Her Majesty.'”

“She will never abdicate because of duty and honour and public service is so deep in her, as it was for him,” a close royal source said.

The queen was dressed in mourning black and separated from her family by social distancing guidelines, with the seat next to her, which would normally be occupied by Philip, vacant.

He went on to say of her public appearances with German Chancellor Angela Merkel and Scotland’s First Minister Nicola Sturgeon: “In three weeks she begins her first summer holiday in Scotland without Philip. It will start at Craigowan Lodge before she moves on to Balmoral Castle a fortnight later.

“More testing times lie ahead. At Christmas, for example, there will be no Philip at her side as she hands out presents to staff.

“Slowly and surely, much of the heavy lifting of monarchy is passing to others. But at 95, the Queen is proof that life can still provide a fresh adventure every day.”

Mike Tindall, who is married to the Queen’s granddaughter, Zara Tindall, told BBC Breakfast that the monarch was “amazing” during  her darkest hour, revealing: “Having to see the Queen make a stand in terms of having to show what the world is at the moment and sit on her own and be as brave as she was, I thought, just summed up her up as a lady. She was amazing.

“Then the funeral finished and it was ‘Get in your cars and go home’, but that is what is allowed, that is what the rules state, so that is what happened.

“It was tough but I thought the actual funeral was done so well that I think he will be looking down and he would have actually been happier about the way it happened.”