King Charles III coronation: Sir Karl Jenkins piece to be played

Sir Karl Jenkins, pictured with BBC Wales presenter Lucy Owen, says the King has always supported Welsh music

Composer Sir Karl Jenkins remembers watching the coronation of Queen Elizabeth II in 1953 as an eight-year-old boy in Swansea.

For the coronation of King Charles III, he will be in Westminster Abbey.

"It's quite a jump isn't it?" said Sir Karl.

More than that, on Saturday, a "haunting, very Welsh" piece he wrote will be performed at the ceremony, played by the coronation orchestra, and joined by royal harpist Alis Huws.

The movement that will be performed is Tros y Garreg, which translates as Crossing the Stone and is based on a Welsh folk song.

It is part of a concerto commissioned by the King more than two decades ago when he was Prince of Wales.

• From sheep pen to palaces for coronation harpist

• New royal harpist for Prince of Wales

• Famous son set to get keys to city

At the time the prince was reintroducing the role of the royal harpist and Catrin Finch, who first held the reinstated role, played Sir Karl's work.

"It's a slow movement based on old Welsh folk tune," said Sir Karl. "It's haunting, it's very Welsh and the story is redolent of a soldier returning home and crossing the stile.

''It starts very quietly, with the strings playing the melody of the folksong, then the harpist is doing this technique called bisbigliando, which means whispering in Italian," he said.

"There's a very virtuoso harp part when the harp goes through the arpeggios, through the chords and it's very emotional."

Sir Karl Jenkin's movement Tros y Garreg is based on a Welsh folk song

Now aged 79, Sir Karl recalled watching the coronation of Queen Elizabeth II in 1953.

"I was sitting in the middle room it was called, but it wasn't the middle, it was a double fronted little cottage in Penclawdd," he said.

"We had one of the first TV screens in the street, in the village I guess...12in (30cm) screen, two rows of friends and neighbours watching."

Seventy years on, Sir Karl will be in Westminster Abbey to witness the coronation in person and listen to Tros y Garreg being performed. The inclusion of Welsh music is said to reflect the King's affection for and support of Welsh culture.

"I am very honoured. It obviously sums up Welsh culture - the harp - and he [the King] has always supported Welsh music," said Sir Karl.

"I don't know whether he chose it, but he was happy to have it there. I know he likes it otherwise he wouldn't have asked me."