Princes Charles, William and Harry were moved by home videos of the Queen, in footage released from a BBC documentary to mark her 90th birthday. Charles expresses his admiration for his mother and how she handled her horse after it spooked during the annual Trooping of the Colour parade in 1981 when a man fired six blanks from a replica pistol. Her horse shied but she was unhurt.

"She's a marvellous rider. She has a marvelous way with horses – she's made of strong stuff," he says in an extract released by the BBC.

In another clip Princes William and Harry are seen watching a home video of a young Charles playing in a garden, with his mother. The Duke of Cambridge noted similarities between his own toddler son, Prince George, and his father. "He walks like George or George walks like him. It's a purpose to the walk," he said.

Elizabeth at 90 – A Family Tribute will be broadcast at 9pm on BBC1 on 21 April.