Today, The Duke & Duchess visited the 1st Battalion Irish Guards at the St. Patrick's Day Parade at Cavalry Barracks, Hounslow to present the traditional sprigs of shamrock to the Officers and Guardsmen of the Regiment.

St. Patrick’s Day is a traditional regimental celebration for the Irish Guards who are part of the Foot Guards Regiment involved in state ceremonial duties.

The Queen is the Irish Guard's Colonel-in-Chief, and The Duke was made Colonel of the Regiment back in 2011.

The Irish Guards are known for their scarlet uniform. You may remember William wearing an Irish Guards Tunic and Forage Cap at his wedding in 2011.

The regiment was formed in 1900 by order of Queen Victoria in response to the courageous actions of Irish regiments in the Second Boer War.

It was Queen Victoria who first instructed all ranks of her Irish regiments to wear a sprig of shamrock in their headdress to commemorate the gallantry of her Irish soldiers.

The tradition of the shamrock comes from St Patrick who was believed to have used it as a symbol of the Holy Trinity when he brought Christianity to Ireland. Bowls of shamrock are flown over from Ireland especially for this parade.

Today, 350 soldiers marched onto the Parade Square at their base at Cavalry Barracks led by their mascot, Domhnall, before The Duchess presented the shamrock to officers and warrant officers, who in turn issue it along the ranks.

The task of presenting the shamrock to the Irish Guards was first performed in 1901 by Queen Alexandra, the wife of Edward VII, and later by Queen Elizabeth The Queen Mother. Since The Queen Mother's death, the presentation has been made by Princess Anne and now The Duchess of Cambridge has taken over the duty. She has attended every year since marriage apart from 2016.

After the parade, The Duke & Duchess got the chance to meet with some of the members of the Regiment, as well as their families, and sit down for some official photos.

A highlight from each parade for me personally is seeing the adorable Domhnall, the Irish Wolfhound who is the Irish Guard's mascot.

The Duchess dressed in festive St Patrick's Day colours for today's Parade at Calvary Barracks with William. ☘️

We saw the return of Kate's bespoke green Catherine Walker coat worn in Stockholm, Sweden in January.

Once again, she paired it with her Troy London faux-fur collar (£65) and cuffs (£40).

Kate also brought back her beautiful Gina Foster 'Meribel Felt Hat With Bow' (originally £535). This hat is made to sit on the right side of the head and is secured by an elastic that sits under the hair. Kate wore this to the 2014 parade too, as well as to the Christmas church service in 2013.

Her gloves are the Cornelia James 'Imogen' merino wool gloves that are available for £70 in multiple colours.

For jewellery, The Duchess had on her Kiki McDonough 'Special Edition Green Tourmaline, Green Amethyst and Diamond Earrings' which were made to celebrate the birth of Charlotte.

She also wore her trusty Tod's block heel pumps and black tights.

The look wouldn't be complete without the Cartier gold three-leaf shamrock brooch, pinned just above her sprig of shamrock. This actually belongs to the Irish Guards, who have loaned it to The Queen Mother, The Princess Royal and now The Duchess of Cambridge.

The Palace has announced two more engagements for The Duchess this week:

On the 21st, she will convene a symposium on the importance of early intervention for children.

On the 22nd, The Duke & Duchess will meet athletes who are part of SportsAid and planning on competing in the upcoming Commonwealth Games on the Gold Coast. They will also help prepare a Commonwealth Big Lunch at St Luke's Community Centre.