Prince Charles is like any normal father and likes to embarrass his sons. Prince William recounted how when he and his younger brother Prince Harry were in school, Charles used to embarrass them during plays by laughing at the wrong places. During a school production, the stage lights and effects started to go haywire, recalled William.

The 33-year-old royal added that both Charles and his grandfather Prince Philip could not help but chuckle. He said that laughing “when things go wrong” runs in the family. Their father would also send the young Princes hand-written notes which were completely indecipherable.

William said that they had to pass them between each other to work out if they were being praised or told off. William and Harry were interviewed for a new documentary “When Ant and Dec Met The Prince: 40 Years of the Prince's Trust,” which will air Jan. 4. The duo talked about their love and respect for their “incredibly hard-working” dad.

William and Harry sat down with comedy duo Ant McPartlin and Declan Donnely popularly known as Ant & Dec for a chat on the occasion of the 40th anniversary of The Princes Trust. William told how their dad was the cause of many blushes for them during their school days. The documentary has been directed by Bafta-winning producer Michael Waldman, who also made the documentary “Our Queen” to mark the Diamond Jubilee in 2012.

Meanwhile, the senior royal who also sat down for a chat with Ant & Dec told that though he loved the company of his grandchildren, he has not changed nappies for Prince George and Princess Charlotte. In the new documentary, the Prince of Wales said that he is thankful he will have them “to look after me when I’m tottering about,” Event magazine reported.

The British comedy duo talked about their chat with the princes in an interview with Event magazine. They told that Charles loved spending time with his grandchildren George and Charlotte. Earlier this year, Charles had enjoyed a spot of gardening with two-year-old George in the gardens of Highgrove.

George and his grandfather planted two new trees in the ground of the country retreat which Charles bought in 1980. “He was lovely about Camilla and the two boys and being a granddad. It was fascinating just to hear him talk like that,” recalled McPartin.