She entered the public consciousness as the middle-class girlfriend who Prince William fell in love with while studying at St Andrew’s University. Since then, her journey has taken her from cruel jibes about being ‘waity Katie’ to a glamorous Duchess who brought new adoration for the Royal family across the globe.

Now, as she marks her 40th birthday, the Duchess of Cambridge is widely revered as the future queen and matriarch who will steer the monarchy through the post-Elizabeth II era. 

Here, we chart her style evolution in 40 images…

“Wow Fergus, Kate’s hot,” Prince William is thought to have whispered to his friend when he saw his fellow St Andrew’s student sashay down the catwalk at the university fashion show on March 26 2002, wearing a see-through dress designed by textiles student Charlotte Todd. It’s said to be the dress which launched the Royal romance, later selling for £65,000.

The Duchess has acknowledged the pivotal role the design played in her relationship with William. On a 2021 visit to her alma mater, she said to a group of students: “I hope you weren’t involved in the fashion show, you never know what you are going to be asked to wear”.

The early years of Kate and William’s courtship mostly took place in privacy, but in December 2006, the future queen was given her first introduction to public life as a Royal consort when she sat on the front row at the Prince’s Sandhurst passing out parade. 

Kate showed early nous for appropriate and respectful Royal dressing, choosing a red Armani coat and wide-brimmed Philip Treacy hat for the occasion even if her mother, Carole Middleton, was criticised for chewing gum as the Queen inspected the cadets.

In 2007, news broke that Kate and William had split and the world’s hopes of a glittering Royal wedding were dashed. Kate showed her mettle, though, and embarked on a series of fun nights out and rowing training sessions as an elegant show of resilience.

While she’d never come close to emulating Princess Diana’s famous revenge dress, there was something subtly sexy about the lace dress she wore to a London book launch with sister Pippa in tow – it was a look that showed William exactly what he was missing and within weeks, the couple had reunited.

On 16 November 2010, it was finally announced that Prince William and Catherine Middleton were engaged following an eight-year romance. This was the moment when Kate truly stepped on to the world stage for the first time as a future queen.

She might have been wearing Princess Diana’s sapphire and diamond engagement ring on her left hand, but she managed to avoid her late mother-in-law’s panic-induced decision to wear a frumpy skirt suit for the engagement announcement. Instead, she had bought one of her favourite slinky wrap dresses by London label of the moment, Issa. It matched the ring beautifully, and made her look youthful and fresh.

Ahead of their wedding, the newly engaged couple toured the UK, introducing Kate to the realities of Royal duties. She showed an early mastery of style diplomacy when she picked out a fluted-hem trench coat by Burberry for a visit to Belfast. The above-the-knee cut chimed with the 29-year-old’s personal style but the decision to wear a heritage British fashion house showed an early grasp on unspoken Royal protocol.

Until her wedding in 2011, Kate’s taste in fashion had been reliably middle of the road, but with judgement that has proved a mark of the woman, she stepped out of her carriage in front of Westminster Abbey in an Alexander McQueen wedding gown that was every bit as dramatic and dignified as the historic occasion and setting demanded.

Created for her by the house’s creative director Sarah Burton with a deep V-neckline, lace sleeves and three-metre train, it was reminiscent of Grace Kelly and the Queen’s bridal looks and proved the start of a long, fruitful collaboration between Burton and the new Duchess.

Although Jenny Packham isn’t a big name on the catwalks, she is superb at red carpet dressing – perhaps because she doesn’t succumb to catwalk edginess. Her beaded, shimmering gowns in pastels shades have never failed the Duchess. 

This first design for Kate, worn just weeks after her wedding, set a precedent – she looked radiant, glowing and at ease with the demand for high-wattage glamour which her new role demanded.

Trust Kate to make a cocktail dress look like the perfect thing for Wimbledon. This tiered, pleated design by Temperley London was literal dressing in the best possible way for her first official appearance at the tournament – a relationship that has flourished over the years as she has become patron and now president of the All England Lawn Tennis and Croquet club.

This white frock may now be more than a decade old, but if she were to trade those nude patent platforms for a pair of mid-heel sandals, it wouldn’t look out of place in the Royal Box today.

It wasn’t long before Kate carved out her own regal style niche, going remarkably casual for some of her engagements and taking part in activities that other Royals might have stood on the sidelines to observe demurely.

The London 2012 Olympics proved to be the perfect platform for this new attitude from the Duchess who set about lending her support to different sports in the run-up to the Games. Here, she dons a Team GB hoodie, coral skinny jeans and Adidas trainers for a training session with the women’s hockey team – her trousers sparked a 471 per cent rise in sales of colourful denims.

The Duchess of Cambridge is widely credited for coming up with the idea for the Head Together campaign, having realised that mental health problems were at the root of so many of the issues being tackled by the charities she, William and Harry represented.

The trio gathered a group of runners to take part in the London Marathon, and while they didn’t run the race themselves, they did take part in a training day. Kate’s outfit epitomises her ability to look practical and polished at the same time; she wore a puffer jacket by ski brand Perfect Moment, those familiar skinny jeans and New Balance trainers. Her £3,100 diamond Asprey earrings were an understated reminder of her Royal status.

The Duke and Duchess of Cambridge have long combined their mutual love of outdoor activities with fundraising for their causes. In 2019, the inaugural Kings Cup Regatta – a revived version of an initiative started by King George V in 1920 – took place on the Isle of Wight, with Kate and William helming a boat each.

The Duchess opted for practical shorts for the event, a style statement which went viral on social media and was seen as a powerful message to women and girls about the importance of getting active.

As a keen tennis fan, the Duchess of Cambrdige was one of the first to congratulate 18-year-old Emma Raducanu when she won the US Open last year and speculation soon began about when the two women might meet and play together.

Weeks later, they showed their support for grassroots sport, playing together at the LTA centre in Roehampton. Kate showed that her eye for quality and timeless sophistication extends to her activewear wardrobe, wearing a tennis skirt and jacket by upmarket French label Poivre Blanc.

Few women would envy the Duchess of Cambridge the task she had before her in July 2013. Baby fever swept the nation (and the world) with the imminent birth of a future monarch. Crowds camped outside the Lindo Wing in anticipation of news of a Royal arrival and after Prince George was born, it was only a day before the Cambridges left with him wrapped in a shawl by heritage British knitwear creators GH Hurt and Son.

The Duchess turned to Jenny Packham for the perfect dress to introduce Prince George to the world. Cleverly, the loose baby blue polka dot creation echoed the Catherine Walker design that Diana had worn on the very same spot following the birth of Prince WIlliam in 1982. It was the start of a tradition which has seen the Duchess wear pieces in tribute to Diana at opportune moments. 

Completed with wedge sandals and a relaxed blow-dry, Kate looked every inch the relaxed and happy new mother with little hint at any anxiety following the frenzied build-up to her son’s birth. 

But there is something quietly momentous happening here, too. The Duchess is on the cusp of motherhood, an experience she went on to describe as one “full of complex emotions of joy, exhaustion, love, and worry, all mixed together. Your fundamental identity changes overnight. You go from thinking of yourself as primarily an individual to suddenly being a mother, first and foremost.”

Inspired by her own experiences, perhaps it’s not surprising that she would go on to launch the Royal Foundation Centre for Early Childhood in 2021. This initiative promotes investment in the first five years of a child’s life to enhance their long-term wellbeing, making the welfare of young children a centrepiece of the Duchess’s personal mission.

The Cambridges created an idyllic family portrait when they arrived as a foursome to the christening of Princess Charlotte as St Mary Magdalene church on the Sandringham estate. From the vintage Silver Cross pram to Prince George’s Rachel Riley outfit (which resembled the red and white set worn by Prince William when he visited his baby brother Prince Harry in hospital in 1984, the Duchess curated a timeless Royal scene.

Her own outfit brought a more modern touch to proceedings. She enlisted Alexander McQueen to create a smart cream dress coat which she paired with a hat by Jane Taylor and jewellery from Mappin and Webb.

The Duchess understands that she must navigate her role within the Royal family with sensitivity, something she did masterfully at the Trooping the Colour parade marking the Queen’s 90th birthday.

The monarch stood out in her neon ensemble but the impact of the occasion was undoubtedly boosted thanks to having the Cambridges by her side, all dressed in co-ordinating pale pastels.

Taking toddlers to a tea party and hoping they’ll be on their best behaviour would be a challenge enough for most mothers, but the Duchess added an extra obstacle to the equation in the form of her cream, pie-crust collar See by Chloe dress for this engagement during the family’s tour to Canada in 2016.

Fortunately, everything went without a hitch and images of George, Charlotte and their parents looking picture perfect as they were entertained by balloon artists and ponies were beamed around the world, bolstering Brand Britain in the process.

Kate and William have guarded their children’s privacy closely, so it’s rare to glimpse an insight into their everyday lives. Which made a family visit to the polo in 2018 even more charming as it offered a chance to see George and Charlotte interacting with their mum and cousins like, well, any other children.

The Duchess was pictured handing out toys from her handbag and laughing along with games, all while wearing a very ‘everymum’ cotton sundress from Zara.

Prince George and Princess Charlotte made their Royal family Christmas debut in December 2019, and again Kate showed her prowess in coordinated, rather than matchy-matchy, family style. 

Charlotte was dressed in a classic bottle green coat by Amaia Kids, a shade which the Duchess picked out with her (recycled) Lock and co hat to complement her very ‘Snow Queen’ Catherine Walker coat. Mother and daughter charmed the crowds during their post-service walkabout and Princess Charlotte even executed the perfect curtsey to round off her festive debut.

Kate has never been one for airs and graces. Never was that better exemplified than when she took part in a Scout camp during a snowstorm in 2013. Where other Royals might have bowed out, she gamely got stuck into activities wearing a khaki anorak, a stylish-yet-practical cap and her favourite Le Chameau wellies.

After years of country engagements and more cosy knits, weatherproof jackets and mud-friendly boots than you could imagine, Kate and William underscored their love for all things country even more with a ‘rural chic’ Christmas card in 2020, showing the whole family in their Norfolk luxe uniforms. The public could be in no doubt as to where the Cambridges’ hearts really lay.

The Duchess is at her best dressed-up for a grand ball, or dressed-down in country attire. Everything about this quilted, nipped-in Barbour, skinny jeans and long tassel Spanish riding boots from Penelope Chilvers (a 17-year-old favourite of the Duchess’s, first seen when she was helping out at a country fair at Blenheim Palace while at university) plays to her strengths. I think these shots will prove as iconic as her wedding dress.

Few would have doubted that the Duchess would rise to the occasion of her first official overseas tour, but nonetheless, the 2011 nine-day visit to Canada was inevitably a test for the newlyweds. Once notably shy, this was almost a make or break moment for Kate, a chance to show that she would be up to the immense scrutiny offered to a future Queen.

Happily, she looked remarkably at ease on the world stage from the beginning when she appeared in this red maple leaf Sylvia Fletcher for Lock and Co hat combined with a white Reiss dress, the colours of the Canadian flag. And the choice of hat was no doubt also a nod to the maple leaf worn by Diana, on her trip to Nova Scotia in 1983. 

Kate displayed her advanced skills in fashion diplomacy on a visit to Bhutan when she wore a skirt inspired by the traditional kira, made from local fabric. She teamed it with a Paul & Joe embroidered wool cape, which was belted with a sash at the waist, creating that very Kate streamlined silhouette.

Even more appropriately, Kate’s modern take on traditional style emulated Bhutan’s own stylish Queen Jetsun Pem.

On foreign tours, the Duchess of Cambridge often eschews her favourite brands for a piece by a celebrated local designer. Almost exactly a year after Britain voted to leave the EU, this trip was designed to strengthen the relationship between the UK and Poland. For it, Kate chose to wear a striking white midi-length cocktail dress with architectural black detailing by one of Poland’s best-known designers, Gosia Baczynska, who described her design as ‘classy and a little bit rebellious’.

When William and Kate landed in Islamabad in October 2019, it was the first time in 13 years that any British Royals had visited the country. Britain, of course, has major historical links to Pakistan and is home to more than a million citizens of Pakistani descent – this visit was a chance for the Royal couple to show how strong ties remain between the two nations.

For the visit, delicate diplomacy was necessary, and Kate wore a number of beautiful, modest outfits; this turquoise shalwar kameez by local designer Maheen Khan was particularly head-turning.

Always famed for striking the right colour note, Kate chose to wear a dress in – what else? – glittering emerald green to visit the Guinness Storehouse in Dublin. Designed by celebrity favourite The Vampire’s Wife, this was a notably modern look for Kate, thanks to the fashionable shoulder pads, frilled sleeves and the three-quarter-length skirt. A meticulous lesson in doing Royal style in a contemporary way.

Diplomacy needn’t always mean pleasing other nations, it can be more personal as the Duchess proved last year. 

Kate had promised four-year-old cancer sufferer Mila Sneddon that she would wear a pink dress when they met, so that she would ‘look like a princess’ – and she delivered on that promise in this £450 shirt-style midaxi by Me+Em. The design sold out online within hours, putting any doubts about the ‘Kate Effect’ to rest.

Four-and-a-half years after she became an HRH, the Duchess made her first appearance at a state dinner for the President of China. She was seated in the most prominent place a female member of the Royal family can sit after the Queen, on President Xi’s right, while the monarch sat to his left.

In a bespoke piece by Jenny Packham, Kate walked in alongside Wang Huning, one of the Communist Party of China’s top leaders. Her dress was a rich red with a sequined bodice – red is of course the colour of China’s flag and symbolises luck and happiness in their culture. The look was finished with the Queen’s lotus flower tiara.

This is a rare foray into Dolce & Gabbana for the Duchess of Cambridge and it is one of her best outfits of all time – the shape is so good on her figure and it works beautifully with the sculpted hat, which she has the height to carry off. Also – her posture has become increasingly regal – a lesson for all of us in how to make clothes look better.

Four months after Britain voted to leave the European Union, and the country was not only at war with itself, but unsure of its relationship with its closest neighbours. Hence the need for Kate who – on her first solo foreign trip – proved to be a uniting force both at home and abroad.

Wearing a pale blue suit by Catherine Walker, she left the British Ambassador’s residence in the Hague to have lunch with the King and Queen of the Netherlands – her job was to charm them, and it was one she no doubt succeeded at.

Somehow it was fitting. Dressed in a black Catherine Walker coat with a Roland Mouret dress, and a veil and pearl choker borrowed from the Queen, the Duchess was pictured arriving at the funeral of Prince Philip, her composure, beauty and dignity combining to offer hope and a vision of the future for the house of Windsor.

In a rare moment, she allowed her eyes to meet the camera, somehow reassuring that the monarchy was in safe hands even as the nation mourned. That quiet confidence and sense of duty was also on display later when she seemed to engineer, gently, the newly arrived Prince Harry into conversation with Prince William, their first chance to talk alone in months.

A relaxed lady in red, Kate hit the perfect note when she showed off an unexpected talent as she accompanied singer Tom Walker on the piano during a performance of his song For Those Who Can’t Be Here during Royal Carols – Together At Christmas for a Westminster Abbey carol concert.

The Duchess – looking wonderfully festive in a Catherine Walker coat – may have been glowing but there was also a sense of a woman firmly in control of her image as never before.

Were Royal watchers surprised by the way the event was broadcast by ITV, not as might have been imagined by the BBC? It certainly happened only a few days after the controversial BBC documentary The Princes and the Press was aired. At the time, the family had issued a joint statement which warned against “overblown and unfounded claims from unnamed sources” and sources suggested the Royals might boycott the BBC as a result.

This look is proof that Kate knew how to buy investment fashion long before she married into the Royal family. This gown by French-born, London-based designer Roland Mouret was from his autumn 2009 collection and is grown-up and elegant without straying into boring territory. That slit to the thigh was a rare show of daring, too, from a usually demure Duchess.

Wearing a one-shoulder white gown by Alexander McQueen, Kate looked spectacular in a very British brand for the 2019 BAFTAS. She accessorised the dress, which featured a gathered waist and white floral appliqué detail on the left shoulder, with glittery pointy toe ‘Romy’ pumps from Jimmy Choo. Jewellery was minimalist, other than a pair of diamond and pearl drop earrings that once belonged to Princess Diana.

Just as everything in the UK seemed to be going to hell in a wind-powered handcart, probably made in China, out stepped the Duchess of Cambridge in the most perfectly-judged display of splendour since Elizabeth I donned a diaphanous ruff and a farthingale constellated with several tons of glittering gold in the famous Ditchley portrait.

Kate wore a diaphanous Jenny Packham dress smothered in gold sequins, with a built-in cape back and matching gold disc earrings – and the nation felt, despite the drumbeat of doom echoing around these islands, its spirits elevate.

This look seems low-key but it was actually quite daring by Kate’s standards. We’re used to seeing her in tailoring, but this off-the-shoulder knitted dress by Barbara Casasola is more relaxed and youthful, as are the peach-coloured Schutz sandals (Kate usually favours courts). She wore the dress a second time for the Action on Addiction gala in 2019.

This Alessandra Rich dress became a modern classic when Kate wore it for Prince Charles’ 70th birthday photographs. With its pointed white collar and cuffs and crisp palette, it demonstrated a level of fashion confidence we hadn’t seen before. It looked just as fresh the following year when she wore it for a visit to Bletchley Park. 

This was the first time we saw Kate delve into the world of vintage fashion, and it was a Fashion Moment. The magenta polka-dot dress by Oscar de la Renta featured a ruffled collar and cinched waist, details that made it reminiscent of Princess Diana’s 1980s style. A brave new Kate was unmistakably emerging by this point.

The Duchess looks wonderful in good trouser-suits, especially mismatched ones like this sharp-lapelled green one from Canadian label Smythe with black flared trousers from Jigsaw which fit her perfectly (she’s a great proponent of having her high street purchases altered). This is much more youthful and sophisticated than some of her early outfits – a sign of how quietly assured she has become.

The Duchess of Cambridge’s widest grins are often reserved for when she is playing sport – whether that means throwing a netball, wielding a hockey stick or – as in this image – running alongside Olympian Jessica Ennis-Hill for a SportsAid event in early 2020. Here, she fuses her natural sporty style with high-street buys: a Mango top, Zara culottes and M&S trainers. Kate at her most relatable.