In 1980, just a year before the wedding of Prince Charles to Lady Diana Spencer, she and Mr Middleton married at a small church in Dorney, Buckinghamshire.
Carole, pictured second from right, has adapted well to Royal life, despite William's pals famously mocking Kate with their 'doors to manual' air hostess impressions
Carole, who was born the eldest daughter of sales assistant Dorothy Harrison and painter Ronald Goldsmith, and grew up in a small house, has fit into royal life with ease
In 1981, Mrs Middleton became pregnant for the first time. Her daughter, named Catherine by her proud parents, would go on to become a royal bride.
Not, however, that her parents knew it at the time. Instead, the Middletons, with Carole unable to work because of her pregnancy, were searching for a solution to a cash flow crisis.
The eureka moment came when Mrs Middleton began making up children’s party bags which she sold to friends and neighbours for pin-money.
Michael Middleton's cousin Matita Glassborow, 63, told the Mail On Sunday: 'Carole was very pregnant with Catherine and couldn’t possibly continue working as an air hostess in her condition.
'So while she was at home waiting for the baby she started making goody bags for children’s parties among her friends.
‘And the business just grew so much that Michael eventually gave up his own admin job with the airline to work with Carole.’
Carole Middleton stands on the balcony with The Prince of Wales and the Duchess of Cornwall with her granddaughter Eliza Lopez following the wedding of the Duke and Duchess of Cambridge
Mrs Middleton went on to have her second child Pippa in September 1983 and James in April 1987, but continued to run Party Pieces at the same time.
By 1995, the company was so successful that it relocated into farm buildings at Ashampstead Common and started employing several members of staff.
Despite their riches, the Middletons lived comfortably, if not lavishly, with the children's private education funded with the help of Mr Middleton's family trust.
Carole and Michael Middleton leaving St Mary's Hospital, Paddington, in July 2013, after visiting their daughter Kate and her newborn baby boy, Prince George of Cambridge
'It made other families feel rather hopeless.'
Nevertheless, all three Middleton children proved diligent students and all went on to university, including the now Duchess of Cambridge who met her husband while at St. Andrew's University.
Prince William was welcomed into the Middleton clan, with Mrs Middleton regularly inviting her daughter's royal beau for Sunday lunch.
Now, like her daughter, part of royal circles, Mrs Middleton has adapted well to life as a royal in-law, despite early hiccups such as the famous incident in which William's friends mocked her with 'doors to manual' air hostess jibes.
But while William's friends proved snobbish, his family was not with the Queen in particular embracing Mrs Middleton.
Indeed, the warm affection and genuine enthusiasm that the monarch has shown towards the Middletons has taken even seasoned courtiers by surprise.
Kate, Pippa and Carol wave to the crowds outside the Goring Hotel ahead of the Royal Wedding in 2011
Despite Carole's more humble beginnings, she has gone on to conquer the fashion world for women of a certain age, too. Pictured here with Pippa at wedding in 2012
She let it be known she thought the family conducted themselves ‘impeccably’ since news of the royal engagement was announced and demonstrated her approval by inviting them to a number of ‘inner sanctum’ events.
These include a private ‘getting-to-know-you’ lunch at Windsor Castle the week before April 2011's Royal Wedding, as well as sending them invitations to her Royal Ascot Week party.
‘The Queen likes them enormously,’ one courtier told the Mail on Sunday. ‘Her decision to invite them to Royal Ascot was a very personal gesture that was entirely her own idea.
'It shows the level at which she has welcomed them into their extended family.’
Pippa and Carole at Queen's club watching Andy Murray in 2013; the family are avid tennis fans
Despite the responsibilities that come with her role as the Duchess of Cambridge, Kate remains incredibly close to her parents.
The Middletons, who live in a £4.8million Georgian mansion in Bucklebury, Berkshire, were the first to arrive at the scene when Prince George was born.
They were also the first visitors to Anmer Hall, with the Duchess of Cambridge hosting Christmas at her Norfolk home last year.
Mrs Middleton has also won plaudits for her style and was even described as 'sexy' by sharp-tongued Chanel designer Karl Lagerfeld.
So popular has her look become, supermarket Asda produced a cut-price range inspired by the Middleton matriarch after customers repeatedly asked for similar clothes.
She certainly looked younger than her years as she set off for Mustique earlier this week, opting for a pair of skinny jeans, a black top and blazer and flat boots - none of which would have looked out of place on one of her daughters.
Carole and Kate often wear similar outfits and opt for the same colour palette
Carole Middleton (L), Pippa Middleton (2nd L), James Middleton (2nd R) and Michael Middleton leave the Goring Hotel in London in 2011 following the Royal Wedding
The family, including Pippa and James Middleton, are holidaying in the tropical luxury of Mustique and staying in a £10,000-a-week villa.
It is understood that the family – accompanied by a team of Scotland Yard bodyguards – have taken over Villa Rocina.
Designed and built in 1971 in the style of a Caribbean plantation, it boasts its own 30ft pool as well as stunning views.
Guests have only to walk a few feet from their garden to snorkel in the crystal-clear Caribbean Sea in front of the house.
Each bedroom has its own en-suite bath and dressing room, and the property also has an air-conditioned gym for guests who manage to tear themselves away from the sun and sand.
Four members of staff – a chef, a butler, a housekeeper and a gardener – will be on hand throughout the family’s stay to tend to their every whim.
Luxury holidays, royal in-laws and a multi-million pound business: It is all a very long way from the humble Southall council flat that Mrs Middleton once called home.
Source: the Dailymail