Creating a life-sized bust in just two hours sounds like a fiendishly difficult challenge even for a renowned sculptor favoured by the Royal Family.

But as these pictures show, Frances Segelman pulled it off in style – despite the “difficult” cheekbones of her celebrated subject Sir Derek Jacobi.

Before an audience at the Film Museum in Covent Garden, she captured Sir Derek’s likeness in clay in just two hours, at the event held in aid of Holloway community centre and charity the Islington Arts Factory.

While she described Sir Derek as a sweet and gentle guy, she said: “It was very challenging – one of the most difficult sculptures I have ever done.

“I did the first half hour standing up, looking down on him. I have never done that before.

“It’s the cheekbones, the planes of the cheek. They were a difficult shape.”

Ms Segelman is best known for her bust of the Queen – which took a year to complete – but she has also carved out a niche when it comes to live demonstrations of her lightning-fast handiwork.

“I have to do positive thinking for two solid hours, otherwise it doesn’t work,” she added.

“It really could not be done without positive thinking all the way through.”