Girls' day out: Queen and Duchess of Cambridge are all smiles at joint engagement

The pair even shared a blanket in the car beforehand.

The Queen and the Duchess of Cambridge's relationship timeline in photos

The Duchess of Cambridge and the Queen have always had a close relationship, with Kate speaking about Her Majesty’s caring nature during an interview to mark her 90th birthday in 2016. With the duchess set to be William’s Queen Consort when he takes the throne in future, she’s got a good mentor in the 92-year-old monarch. Kate began dating William at university in 2003 and she reportedly met the Queen for the first time at  Peter and Autumn Phillips’ wedding in 2008.  William proposed in November 2010 and the couple were married in April 2011, when the Queen gave them the titles of the Duke and Duchess of Cambridge. Kate and Her Majesty had their first official engagement together in Leicester in March 2012, to mark the first date of the Queen’s Diamond Jubilee tour of the UK. Before that, they viewed Kate’s Alexander McQueen wedding dress on display at a Buckingham Palace exhibition. Since then, they’ve hosted receptions at the palace together and have been present on the famous balcony for annual events such as Trooping the Colour. They also enjoyed a girls day out together with Camilla, Duchess of Cornwall in 2012, when they visited London’s Fortnum & Mason. The Duchess of Cambridge appears to have taken some style lessons from Her Majesty, favouring block coloured shift dresses and bold coats. She’s even borrowed jewellery from the royal vaults, including tiaras, brooches and earrings. Take a look at Kate and the Queen’s best moments together over the years.

Kate Middleton Puts a Regal Spin on St. Patrick’s Day Style

The Duchess of Cambridge opted for a sleek olive coat by Alexander McQueen.

Kate stuns in green McQueen coat for St Patrick's Day parade

The Duchess of Cambridge turned to her favourite fashion designer for the event.

Kate Middleton's wardrobe mishap proves she's just like us

Royals, they're just like us!

The Duchess of Cambridge cleverly altered an old dress for a gala last night

Same dress, but different.

Princess Beatrice makes first official appearance with boyfriend Edoardo Mapelli Mozzi

It is the first time they have been pictured together.

Kate Middleton and Melania Trump love this $1,800 blouse — shop the look starting at just $55

Melania Trump is also a fan.

Kate Middleton wears Melania Trump's infamous Gucci p***y-bow blouse

Trump notoriously wore a fuchsia version of the designer blouse to the second presidential debate in 2016, days after her husband's "grab them by the p***y" quote was leaked.

What Kate and Meghan's body language says about their rumoured rift

The duchesses were reunited at the Commonwealth Day service.

8 bags that look like Kate Middleton’s $494 'it' purse — for less

Kate Middleton's Manu Atelier handbag retails for over $400. Here's how to get it for less.

Who is the Duchess of Cambridge's 'private dressmaker?'

It's a bit of a mystery.

Meghan Markle and Kate Middleton reunite to celebrate father-in-law Prince Charles

The royals stepped out in style for a Buckingham Palace reception honoring Prince Charles.

Kate Middleton wore the cutest sneakers — and they're $44 right now

Shop Kate Middleton's super chic New Balance sneakers on sale for a limited time!

Kate Middleton pulls pints in Belfast while wearing a $2,480 Missoni dress

The duchess went designer as she got behind the bar and pulled pints of Harp Ice.

The princess and the pea coat: Get the royal look for less

Inspired by the royals, the pea coat is the only jacket you need this season.

Duchess Of Cambridge flawlessly pulls a pint in a designer gown at Belfast's Empire Music Hall

Kate stepped out in an elegant evening look.

Kate Middleton Looked So Cute Playing Soccer With Prince William Today

Why Kate Middleton and Meghan Markle can't accept free clothes

Everything the stylish royals wear must be paid for.

Duke and Duchess of Cambridge pay surprise visit to Northern Ireland

The pair showed off their ball skills at Windsor Park stadium, in Belfast.

Why the Duchess of Cambridge and Doria Ragland were not at Meghan's baby shower

There's a pretty reasonable explanation behind their absence.

Why has the coverage of Meghan and Kate's fashion choices been so different?

Royal correspondent Omid Scobie and fashion director Amber Graafland discuss on The Royal Box.

Kate Middleton and Prince Louis Went on a Valentine's Day Walk in the Park

Kate is almost never seen out in London, so this is exceptional.

Duchess of Cambridge addresses struggles of motherhood: 'I was very naive as a parent'

Kate opened up about her own experiences during a mental health in education conference.

Kate Middleton Just Wore the Perfect Work-Appropriate Look

She's stylish and warm in modern tweed.