Peter Phillips and his wife Autumn told monarch of their pending marriage split last summer

For both parties it looked like a marriage made in heaven — a classic case of opposites attracting.

Peter Phillips had all the prestige of being the Queen’s favourite grandson. Handsome, confident and popular, he enjoyed every advantage of his birthright without the impediment of a title or the inconvenience tof actually having to work for the Royal Family.

The young woman he married came from very different beginnings. Canadian management consultant Autumn Kelly was a hairdresser’s daughter from a tough, working-class suburb of Montreal. 

One brother was a bricklayer, another a chef and there was a wayward uncle who once ran a strip club.

What both Peter and Autumn possessed, however, was a love of making money. Now they will have to divide their ample assets. After all, this is a couple who even made money out of their wedding day, selling the pictures to Hello! magazine for a reported £500,000.

Eight years later, Peter’s celebrity management company was paid £750,000 to oversee a £150-a-head party in the Mall to celebrate the Queen’s 90th birthday.

And only last month — as revealed in the Mail — Phillips drew withering criticism for using his family connections to sell milk on Chinese TV. His firm has also negotiated deals for his Olympic medal-winning sister Zara.

So far, so lucrative. But Peter and Autumn have made the brutal discovery that by financially enriching themselves through their royal links, they have opened up their private lives to scrutiny.

It is an object lesson for Prince Harry as he and Meghan begin their post-royal life as paid guests of a banking giant.

All the same, the couple’s decision to part after almost 12 years of marriage and two daughters — Savannah, nine, and seven-year-old Isla — has not only saddened the Queen and members of the Royal Family but also surprised courtiers.

For a long time, Peter, 42, filled a special role in the Queen’s family. He kept an eye on his cousins Prince William and Prince Harry, who looked up to him — and was their constant companion in the dark days immediately after the death of Princess Diana.

Recently he has been a regular fixture at the bedside of his grandfather Prince Philip, and last month he was the only other family member present at Sandringham as the Queen, Prince Charles and William struck the agreement with Harry that allowed him to walk away from his royal life.

Yesterday, in a joint statement, Peter and Autumn, 41, described their separation as ‘sad but amicable’ and said it was ‘the best course of action for their two children and ongoing friendship’. What also became clear is that this was no new development.

A divorce is already under way and they announced that they will be sharing custody of Savannah and Isla.

They have denied reports that the decision to split had anything to do with Autumn wishing to return to her home country. It was suggested, wrongly, that she might have been influenced by Harry and Meghan’s departure from the UK to Canada.

In fact, the couple separated long before news about the Duke and Duchess of Sussex’s shock move was disclosed.

Peter spent Christmas at Sandringham with the rest of the Royal Family but without Autumn. Last month he hosted his annual shoot on the Norfolk estate and once again his wife was absent.

I understand they told the Queen during a private visit to Balmoral late last summer.

During their stay, Autumn travelled to church with the Queen, who has grown very fond of her spirited granddaughter-in-law. She urged them not to make a hasty decision.

But the couple, who also attended the annual Braemar Gathering Highland games in September with the Queen and Prince Charles, had already told Peter’s mother and father, Princess Anne and Captain Mark Phillips, and Autumn’s divorced parents, Brian and Kitty, of their plans.

For now at least, Autumn and their daughters remain at the couple’s country home, a barn conversion on Princess Anne’s Gatcombe estate near Minchinhampton in Gloucestershire.

Peter has been spending part of his working week in London — there is a flat in Kensington — and weekends at the family home.

While it is unclear where they will live in the immediate future, Autumn has no plans to go home to Canada. She has put down strong roots in the Cotswolds and is said to have a wide circle of friends.

So what prompted the split?

Some are bound to think of that old cliché that an apple doesn’t fall far from the tree and wonder if Peter is a chip off his father’s block.

Mark Phillips’s 19-year marriage to Princess Anne was hardly a textbook success story. It ended in 1992; she went on to marry a former royal equerry, Vice Admiral Sir Tim Laurence — and five years later Phillips married U.S.-born dressage rider Sandy Pflueger.

That marriage produced a daughter — a half-sister for Peter and Zara — but ended in divorce in 2012 amid reports that he had begun an affair with another U.S. equestrian, Lauren Hough, almost 30 years his junior. He also fathered another daughter following an affair with a New Zealand art teacher in the 1980s.

Autumn’s arrival in the Royal Family was seen as a sign of change. State school-educated, she grew up in a home where money was tight but was remembered at her old school as someone who liked to party.

Friends say this is one attitude that hasn’t changed since she became the Princess Royal’s daughter-in-law. 

‘She is part of a fairly noisy Gloucestershire set and is a bit of a party girl,’ I am told. ‘You’ll see her downing cocktails while sitting on friends’ knees having fun.’

Certainly, this is far from the conventional image she has presented as a much-admired and dutiful member of the Royal Family. 

‘She’s a great mother and everyone thinks she has fitted in really well,’ says a figure close to the Queen. 

‘She’s a favourite of the Queen — but then so is Peter. He was her first grandchild, the first to marry and the first to make her a great-grandmother.’

Sadly, Peter Phillips will now be the first of the Queen’s grandchildren to divorce.

The truth is that being neither a royal nor exactly a commoner has been both a burden and a blessing for him.

It was commendable that on his birth in 1977, Princess Anne declined her mother’s offer of a title. How the Queen would have loved to bestow one to mark the arrival of her grandson during Silver Jubilee year.

But Anne took the view that Peter and his sister Zara, who is married to former England rugby star Mike Tindall, should make their own ways in the world. They would not be working royals.

For Peter, that has meant a decidedly more low-key life than that of his first cousins William and Harry and, to a lesser extent, Princesses Beatrice and Eugenie.

And until this week’s news, life has dealt a remarkably benign hand to the young man whom Prince Philip christened ‘the winner’ because of his independence. Easygoing and rarely flustered, he wore his royalty lightly.

‘Where Prince Andrew will never cease dropping his mother’s name — though he refers to her as Her Majesty — at any opportunity, Peter does his best never to mention his grandmother,’ says a friend.

Alas, this modesty never applied to his money-making.

All the same, he was allowed to grow up removed from the royal spotlight that might have shone on him as the Queen’s grandson. 

He was educated at Port Regis — where a parent says he was ‘one of those prep-school gods, handsome, marvellous at rugby and admired by everyone’ — and then Gordonstoun, where he rose to be head boy, or ‘guardian’ as they call it.

The school has strict rules on alcohol, and even those pupils old enough to consume it are limited to three glasses of beer, cider or wine at the Saturday socials.

‘But that didn’t stop Peter,’ said a contemporary. ‘He had his own secret supply.

‘On a Saturday he would go into Elgin, the nearest town, load up a taxi with cans of beer, smuggle them into school and hide them in his trunk.’

So when the official supply had run out, Peter could always be relied upon to produce a bit more.

‘When he was guardian he used to give jolly good parties in his room,’ the friend recalled. ‘There would be music playing and we’d be drinking beer, boys and girls together, and there would be a bit of snogging.’

It was just one cherry brandy that got his uncle Prince Charles threatened with the cane when he was at Gordonstoun.

But Peter was never caught and left the school with three A-levels and an excellent final report. His romances, too, remained very much his own affair.

At the co-ed school he dated several fellow pupils. One was army officer’s daughter Penny Taylor, two years his senior; another was Emily Ayre, the daughter of an Edinburgh businessman, who was two years his junior.

After graduating from the University of Exeter with a degree in sports science, Peter worked for Jaguar as a corporate hospitality manager before taking a position at the Williams Grand Prix Engineering team.

From then on, there was always a pretty girl on his arm.

He dated American cod-liver oil heiress Elizabeth Iorio, who shared his cosy Belsize Park flat but who, after they parted, suggested he needed to ‘grow up’. Then came a four-month romance with British Airways stewardess Tara Swain.

It was on a business trip at the 2003 Montreal Grand Prix that he met the glamorous Autumn, who was working as a Budweiser girl — a model promoting the beer — at the event and didn’t realise he was the Queen’s grandson.

The pair embarked on a relationship and she moved to London. Four years after that, Peter popped the question.

Autumn, who was born and brought up a Roman Catholic, renounced her faith shortly before their wedding at St George’s Chapel, Windsor, in 2008, so her husband-to-be didn’t have to give up his claim to the throne.

But such sensitivity was soon forgotten amid a furious public backlash over the couple selling their wedding photos, which was branded a ‘serious error of judgment’ by an MP at the time.

When photos were later released of their honeymoon in South Africa, it prompted speculation that they’d had free accommodation or a reduced rate in exchange for publicising their stay.

These days, they are no strangers to leveraging their royal celebrity.

Even so, friends can’t help wondering if Peter agreed to his infamous milk commercial to help him through the unpredictable costs of divorce.