The 16-year-old boy, who cannot be legally identified, robbed the singer of his £17,000 Rolex watch while he was out walking with his son.

The 52-year-old who is originally from Bangor, North Wales, was walking along Chiswick High Road in west London at around 5.40pm on 7 July when he was attacked.

The defendant was due to stand trial at Wimbledon Youth Court on Thursday but pleaded guilty to robbery and possession of an offensive weapon after he turned up late for his trial, which was already under way.

Prosecutor Robert Simpson told the court Mr Jones was walking with his son when he was "approached by a youth in a black tracksuit top and bottoms and wearing black trainers".

"(The defendant) produced a knife in the form of a machete from his tracksuit bottoms and threatened to cut off his arm and made various other threats in order to obtain the Rolex watch Aled Jones was wearing," Mr Simpson said.

He added: "Aled Jones immediately handed it over and the defendant made off."

CCTV was gathered from the area and the teenager was arrested at his home in west London.

Mr Jones, best known for singing Walking In The Air as a child and presenting Songs Of Praise, waited with his son for almost two hours to give evidence via a video link.

It was turned on for about a minute and he nodded and thanked court staff as he was told the teenager had entered a guilty plea.

District Judge Andrew Sweet told the boy the offending was "very, very serious" and the case was adjourned while reports were prepared.

He was released on bail but will be told where to sleep and live by the local authority.

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The case will be heard again at Ealing Youth Court on 12 September.

The defendant was told by the judge he could not guarantee the case would not be sent to the crown court at that hearing.