She started dating the future king as an unknown undergraduate but in an extraordinary rise to the top of society, Kate has become the mother of Britain's future monarch.
However, the Duchess of Cambridge's route to royalty was not entirely smooth as it came after several, sometimes lonely. years of waiting for Prince William to decide if she was 'the one'.
Legend has it that as a schoolgirl she even used to lie in her dormitory bed gazing at a picture of her future husband - now the father of their first child.
Happy couple: The Duke and Duchess of Cambridge at their graduation ceremony at St Andrews University in 2005. Almost eight years to the day after this moment, Kate has had their baby
So for the unassuming girl originally from near Slough, it seems that in the end dreams can come true.
The couple's thoroughly modern relationship has seen them become the most senior members of the Royal Family to live together before marriage, an unthinkable arrangement even a couple of decades ago.
And unlike the Queen, who promised to obey Prince Philip when they married in 1947, Kate pledged only to 'love, comfort, honour and keep' her husband two years ago.
Her relatively humble background also sets her apart from other British royal women.
But it was not always certain they would make it to Westminster Abbey, because the couple had split in 2007.
Memories: A baby Kate Middleton is seen in the arms of her mother Carole as proud father Michael looks on on the day of their daughter's Christening
Much loved: Kate as a toddler clambering over some rocks on holiday in the Lake District with her parents, who met working for British Airways
Kate as a sweet four-year-old on holiday in Jordan with her family in a series of pictures from her parents' own albums
Rising up: After her parents made their fortune selling party goods, Kate (centre) was sent to the £30,000 a year Marlborough School
Keen sportswoman: Kate was a member of the rounders team (front row, left) during her time at St Andrew's School in Berkshire
A friend said at the time that William had believed he didn't want to be 'nailed down'.
Kate was devastated and a friend at the time said about her hopes of getting engaged to the future king: 'As far as she was concerned, it wasn't a question of "if ", just "when".'
After living the single life for several months, the first sign that the couple were rekindling their relationship came after it emerged that Kate had secretly met with the prince at his Clarence House apartment to discuss their split.
Contrast: Prince William, seen as a child with his parents and brother Harry in a touching picture that adorned a family Christmas card in 1987, became second in line to the throne at birth
Privilege: While Prince William, seen with his mother and brother at the piano in Kensington Palace as a child, was born into a life of privilege, Kate's background was humble by comparison
Childhood: Princes William and Harry are seen as little boys with their childhood nanny, Olga Powell, who developed a close bond with her young charges
Memorable day: Prince Charles and Camilla Duchess of Cornwall attended Prince William's graduation ceremony at St Andrews University, as did the Queen and Prince Philip
She was then among a number of friends William invited to a party a couple of weeks later at his Army barracks at Bovington, Dorset, where they were seen kissing on the dance floor.
From then there was no looking back for the girl from Berkshire, who got engaged to William in November 2010 after he proposed using the engagement ring that belonged to his mother.
They married the following April and now are about to have their first baby.
Model: Kate took part in a student fashion show while at university in St Andrews, where she famously caught the eye of Prince William
Early days: The Prince and Kate at a rugby sevens event in 2003 when they first started going out
Successful: The future queen at her graduation ceremony at St Andrews University
Strengthening bond: Kate Middleton and her parents Carole and Michael were in the stands at Prince William's passing out parade at Sandhurst in 2006
Kate was born in January 1982 to former British Airways flight attendant Carole, and father, Michael, who once worked for the same company making sure flights left on time and with the correct cargo.
They met while working for BA and started their married life in a flat in Slough, just across the river from the future in-laws at Windsor Castle.
But it is the family business Party Pieces, launched by Mrs Middleton from their home in Berkshire, which founded the family's wealth and gave their daughter entry into higher social circles.
Out on the town: William and Kate after a party at Mahiki in 2006 at a time they appeared to be going strong
Cracks: Prince William and Kate Middleton watch England at Twickenham in February 2007, but within weeks they had broken up as William reportedly felt pressure to get engaged
Split: The couple broke up shortly after the Cheltenham Festival in March 2007
Getting on with life: Kate walks back into her parents' home in Bucklebury with a box of belongings after the announcement of her split from Prince William
Partying apart: Days after the split Prince William appeared at Elements in Bournemouth, and was pictured with his hand apparently on Brazilian Ana Ferreira's breast
Social life: Kate did some partying of her own while the couple were apart, including donning a pair of bunny ears for this June 2007 event
Carole had started making birthday party bags on the kitchen table and ended up forming a lucrative business that would make them millionaires.
When she was old enough, Kate was sent the first step up the social ladder by attending the all-girls school Downe House in Berkshire, but it was not a success.
According to rumour, Kate was miserable and bullied there, lasting just two terms before moving to the co-educational Marlborough College, where fees are now £30,000 a year.
Back together again: Prince William and Kate are snapped leaving Bouji's nightclub in October 2007, appearing more in love than ever
Young love: The couple at RAF Cranwell in 2008 when William received his wings
Betrothed: After a few bumps in the road, Kate and William announced their engagement three years ago
A very modern engagement: Clarence House announced the news of their 2011 marriage on Twitter
Road to happiness: Prince William and Kate Middleton posed for an official engagement portrait in November 2010 after he proposed with the engagement ring that belonged to his late mother
Happy together: Another official engagement photo taken by celebrated photographer Mario Testino at St James's Palace
Happy day: Kate's pregnancy came around 18 months after their wedding at Westminster Abbey on April 29 2011
All smiles: Two years after marrying Prince William in a lavish ceremony watched by millions, Kate is to give birth to the royal couple's first child
Married at last: The Duke and Duchess of Cambridge waved as they set off from Westminster Abbey following the ceremony
She then read History of Art at the University of St Andrews, where she met Prince William.
Since then Kate and her family have been the subject of intense scrutiny.
Royal consorts like the Duchess have traditionally come from the ranks of Britain’s aristocracy or from other European royal houses.
But numbered among the Middletons' ancestors are Northumbrian miners and Kent builders and labourers.
Perfect princess: The Duke and Duchess of Cambridge at an event shortly before William's 30th birthday last year
On tour: The couple's trip to the Far East and South Pacific in June 2012 was a huge success - but Kate battled drama back home after topless pictures of her were published in Europe
New look: A week before she announced her pregnancy, the Duchess showed off a different haircut as she attended an event at the Natural History Museum
Pregnancy: The couple were forced to announce their baby news early after Kate was admitted to hospital with acute morning sicknes
Easier time: The rest of the Duchess's pregnancy went more smoothly and she was able to attend functions
Shopping trip: The Duchess of Cambridge was spotted with her mother Carole in South Kensington, where they bought a Moses basket for the imminent arrival of the royal baby
Glowing: Kate looked radiant throughout her pregnancy
Taking it easy: The Duchess, her husband and their dog Lupo were given a lift home from Wales by friend Simon Oliphant-Hope in his helicopter on June 25
The Duke and Duchess of Cambridge arrive at Westminster Abbey for the Queen's Coronation Service last month
TIMELINE: THE ROYAL ROMANCE
SEPTEMBER 2001: Prince William and Kate Middleton meet at St Andrews University.
MARCH 2002: William pays £200 to watch Kate modelling a sheer black lace dress in a fashion show.
CHRISTMAS 2003: Rumours abound that the pair have started dating.
MARCH 2004: The romance is exposed after they are pictured on the ski slopes of Klosters together.
JULY 2005: The pair enjoy a romantic holiday at the Lewa Downs game reserve in Kenya.
JANUARY 2006: William is photographed kissing Kate in public for the first time during a skiing break in Klosters.
DECEMBER 2006: Kate makes her most significant appearance to date as she turns up to watch William graduate as an Army officer at Sandhurst.
APRIL 2007: William and Kate are confirmed to have split but they secretly reunite within weeks.
OCTOBER 2007: The couple are pictured back together for the first time.
APRIL 2008: Kate is at William's graduation ceremony from the RAF, suggesting the couple's relationship is now permanent and has the approval of senior royals.
JANUARY 2010: Kate watches as William graduates on an advanced helicopter training course and receives his flying badge from the Prince of Wales.
FEBRUARY 2010: William says 'You'll have to wait a while yet' when asked about the prospect of a wedding.
OCTOBER 2010: The couple are pictured in public together at a friend's wedding, sending speculation of an engagement to fever pitch.
NOVEMBER 16 2010: The couple's engagement is announced by Clarence House.
APRIL 29 1011: Couple are married at Westminster Abbey.
DECEMBER 4 2012: Announce pregnancy after Kate falls ill with acute morning sickness.
JULY 22 2013: Duchess gives birth to their son.
There have been ‘commoners’ (non-Royal brides) in the Royal Family before, notably Queen Elizabeth, the Queen Mother, and Lady Diana Spencer – but both were the daughters of earls.
Critics within Prince William's circle are said to have constantly made snide remarks about her middle class background and how they believed her family unsuitable.
Her siblings, James and Pippa, have developed an uncomfortable habit of using their sister's high profile to make names for themselves and to further their careers.
Pippa has previously been accused of cashing in on her royal connections and writes for Waitrose magazine in a column called Pippa’s Friday Night Feasts.
In the latest issue, she presents a Mexican feast, although admits she has never been to Mexico and took her inspiration from a local Mexican restaurant.
She has responded to criticism of ‘glaringly obvious’ advice in her entertainer's bible Celebrate – such as her observation that turkeys, ‘because of their size… are perfect for feeding larger gatherings’ – by arguing she has to ‘cover the basics’.
She also laughed off as ‘all good fun’ a parody Twitter account, @pippatips, which offers spoof advice such as: ‘Enjoy a glass of water by getting a clean glass and pouring in water from a tap or bottle. If you like cold water, add ice.’
James dropped out of Edinburgh University to start his own business, the Cake Kit Company, two years ago.
Explaining his decision, James said he just didn't feel comfortable wasting his life in a classroom and wanted to try his hand at entrepreneurship.
But few young entrepreneurs have been lucky enough to secure interviews in several national newspapers and society magazines on the back of it - all with the obligatory mention of his famous sister.
He is now likely to marry model and TV presenter Donna Air.
Kate's mother Carole, who comes from a working-class background --descending from a line of impoverished Durham miners and builders has, often unfairly, borne the brunt of much of the criticism.
She was lambasted for chewing nicotine gum throughout William's passing-out ceremony from Sandhurst and when the couple briefly split was humiliated by claims that so-called friends of the prince would snidely say: 'Doors to manual' when they saw Kate in reference to her previous profession in the air.
There is the suggestion - rejected by family friends - that Carole even deliberately encouraged her daughter to apply for St Andrews with the hope of bagging a prince.
Family: Carole, Michael, James and Pippa Middleton leaving The Goring Hotel on the day after Kate married
Read more: http://www.dailymail.co.uk/news/article-2350751/Duchess-Cambridge-Kate-Middletons-route-royalty-middle-class-beginning.html#ixzz2Zo6LcGIk
Follow us: @MailOnline on Twitter | DailyMail on Facebook
