Watch Prince Charles sing for Ant and Dec in documentary

He is next in line to the throne, but that didn't stop Prince Charles from showing off his singing talent for TV presenters Ant and Dec during an evening at his Scottish home Dumfires House.

The presenting duo and fellow dinner guests including Rod Stewart and his wife Penny Lancaster were treated to a rendition of Aberdeenshire song The Bonnie Lass o’Fyvie, which will be shared with the public in an ITV documentary When Ant and Dec Met The Prince: 40 Years of the Prince's Trust.

Ant and Dec were joined by their wives Lisa Armstrong and Ali Astall, when they were invited to Dumfries House during the year they spent shadowing the royal for the documentary.

The pair, who usually present entertainment shows such as Britain's Got Talent, were clearly impressed by the royals' tune. Ant said about the Prince's performance: "He done all right didn't he", to which Dec replied: "It's a yes from me." Ant then quipped: "He's through to the next round".

The Geordie presenters secured personal interviews with Charles' nearest and dearest for the documentary, in which the grandfather to Prince George and baby Princess Charlotte also reveals he is enjoying having a grandaughter.

In an interview, Prince William also tells trust ambassadors Ant and Dec about how fatherhood has changed him and made him realise "how precious life is".

"Just because you realise how precious life is and it puts it all in perspective. The idea of not being around to see you children grow up [is horrible]," said the 33-year-old, who lost his own mother, Princess Diana, when he was only 15 years old.

The Princes' trust was set up by Prince Charles in the 1970s. The charity aims to help disadvantaged children "who are unemployed or struggling at school, to transform their lives."

At the end of the documentary Charles, 67, revealed he hopes one of his sons "might take an interest" in taking over the Prince's Trust eventually, adding: "Cause I’m probably getting past my sell by date now."

When Ant & Dec Met The Prince: 40 Years of The Prince’s Trust airs on Monday at 9pm on ITV.