Best photos of Kate Middleton's reunion with Queen Maxima and Queen Letizia at Order of the Garter service

The Duchess of Cambridge enjoyed a special reunion with Queen Maxima of the Netherlands and Queen Letizia of Spain as the royals attended the Order of the Garter service in Windsor on Monday. The stylish trio were supporting their husbands, who are members of the Order – William as a senior British royal, and King Willem-Alexander and King Felipe as Knights of the Garter. Knights of the Garter are chosen personally by the Queen to honour those who have held public office, who have contributed in a particular way to national life or who have served her personally.

Kate looked incredibly stylish for the event, wearing a white Catherine Walker coat and a hat by Lock & Co, while Maxima was stunning in a blush pink dress that featured a belt and cape. Letizia showed off her sartorial prowess in a silk grey and white shift dress and black fascinator.

Let's take a look at the best photos from the Order of the Garter service…

King Felipe was also invested as a Supernumerary Knight of the Garter, accompanied by his wife Letizia.

A closer look at the Duchess of Cambridge's white coat that featured black detailing.

Maxima and Kate were spotted chatting at the Galilee Porch while waiting for the procession to begin.

The Duchess of Cornwall was also present, looking pretty in a pale pink Anna Valentine coat dress with a Philip Treacy hat.

The Countess of Wessex embraced the sunshine in a Suzannah dress and Jane Taylor hat.

The Dutch queen looked incredibly proud of her husband.

The Queen was pictured arriving at the ceremony following her lunch with King Felipe and King Willem-Alexander.

Every year to celebrate the iconic Garter Day, the Queen and the Knights take part in a procession wearing grand velvet robes, glistening insignia and plumed hats. The ceremony takes place at Windsor Castle, accompanied by a marching band and Officers of the Order, all in grand ceremonial dress.

Established in the 14th century, the Order of the Garter, with St George as its patron saint, is the oldest national order of knighthood and Britain's most senior order of chivalry. It is also one of the most exclusive – only 24 knights are allowed at any given time, along with the British monarch and the Prince of Wales.

Prince William and Prince Charles took part in the procession.

King Felipe of Spain and King Willem-Alexander of the Netherlands made their debut at the ceremony.

After the 40-minute service, the Queen travelled up to the state apartments in a carriage with Prince Charles and Camilla to applause from the crowd.

Felipe and Letizia were in the second carriage with the Duke and Duchess of Cambridge.

Felipe waved to crowds.

The Duke of York sat with Willem-Alexander and Maxima in the third carriage.