The Prince of Wales addressed troops, at Combermere Barracks in Windsor, for the first time since becoming colonel of the regiment in December.

William was bestowed the title by the King, who previously held the rank before becoming monarch.

He also met members of the 5th Royal Australian Regiment and spoke to them about their role in training Ukrainian armed forces in the UK.

As is tradition for the parade, the prince presented leeks, which feature on the cap badge of the regiment, to the officers and guardsmen.

William, who was joined by his wife, Kate, the Princess of Wales, also gave a speech to rank-and-file soldiers where he said the Welsh Guards' "banter" had helped him get through his own time in the regiment.

He told them: "I am both honoured and delighted to be standing here in front of you today as your new Colonel.

"At the same time, I'm sorry that my father couldn't be here with us today to say farewell, but I know he would talk of his fierce pride and admiration for you all, and of his own sadness to be moving on from an appointment he held so dear since 1975.

"While they may not have been my easiest or driest days in the Army, my memories with the Welsh Guards Sniper Platoon Salisbury Plain are some of my best.

"Another key milestone in my life was also shared with the Welsh Guards, this time in the jungles of Belize as I received my A-level results over the Bowman Radio.

"Many of you will know the feeling of being in the jungle; you're incredibly hot, continuously soaking wet and with nowhere to hide from potentially horrendous results, it could have been a really bad day.

"Ultimately though, it was the camaraderie, the togetherness, and of course the banter of the Welsh Guards that got me through that period, and it's a time I look back on fondly."

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He finished the speech with the regiment's motto, Cymru am byth, Welsh for Wales forever.

In a post on the couple's Twitter page, he wrote: "Honoured and delighted to be the new Colonel of the Welsh Guards and to join friends, families and loved ones for the St David's Day parade at Combermere Barracks.

"Our friends in the 5th Royal Australian Regiment are here too and it was great chatting to them about their role training Ukrainian Armed Forces in the UK.

"Wishing a very Happy St David's Day to everyone celebrating today!"

On Tuesday, the pair took part in an endurance spin class during a visit to an Aberavon leisure centre.

The royal couple joined gym-goers at the endurance cycling session in South Wales, and were challenged to see who could cycle the furthest in 45 seconds while riding a virtual race in the Italian mountains.

Kate, who was still wearing her high-heeled boots, won the race.

Away from their race, the pair toured the centre's sports hall and swimming pool, and met children from the local Tywyn Primary School, who were taking part in various indoor sports.