How Meghan Markle's outfit broke strict royal protocol at the Queen's birthday celebration.

Meghan Markle is no stranger to breaking the royal rules.

From changing her vows at her royal wedding to Prince Harry to attending events without wearing pantyhose, the newly-appointed Duchess of Sussex is bending the royal rules one step at a time.

And now, Meghan’s done it again, attending the Queen’s official birthday celebration, Trooping the Colour, wearing a rule-breaking dress.

The 36-year-old ex-Suits actress arrived at the event in a horse-drawn carriage with her husband Prince Harry, wearing an off-the-shoulder pastel pink dress designed by Carolina Herrera.

But according to The Sun, Meghan broke royal protocol with her dress, as "fashion tradition usually dictates that royal women do not wear off-shoulder or other more revealing styles".

The dress, which she wore with a matching hat, was reminiscent of her off-the-shoulder Givenchy wedding gown.

The Sussexes arriving at Horse Guards #TroopingTheColour #DuchessOfSuccess pic.twitter.com/hZi0zDJFnz

— Omid Scobie (@scobie) June 9, 2018

Trooping the Colour was Prince Harry and Meghan Markle's first appearance since their honeymoon.

The Duchess of Cambridge, Kate Middleton, also arrived at the event in a horse-drawn carriage, alongside Prince Charles' wife, Camilla – both wearing light blue dresses.

Prince William and Prince Harry also attended in military dress uniforms.

Trooping the Colour is the Queen's annual birthday celebration event. Although she celebrated her 92nd birthday in April, her public birthday is celebrated every year on the second Saturday of June.

According to the royal family's website, the event involves over 1,400 parading soldiers, 200 horses and 400 musicians.

The highlight of the day involves members of the royal family gathering on the balcony of Buckingham Palace, where they wave to the crowds and watch the RAF's Red Arrows fly past.

The Queen's great-grandchildren were also present on the balcony, and they understandably stole the show.

While singing the British national anthem, Peter and Autumn Phillips daughter, Savannah was seen clamping her hand over Prince George's mouth to stop him from singing.

Princess Charlotte, 3, also had a fall on the balcony, but luckily her mum, Kate Middleton, was there to comfort her.