Clover, voiced by Gemma Arterton Star Wars actor Boyega, 26, said the realism created by the new animation techniques will increase the “emotional stakes” for viewers.“I was also curious as to how they were going to do this, because the 1978 film was in 2D and it was devastating,” said Boyega, who voices Bigwig.“I was devastated, I can’t lie. It was too much – it was bloody and looked a bit strange and as a kid taking that in was very scary.”Hoult, 29, who plays Fiver, said the story is “scary at times” but “not unsuitable for your children to be watching with you”.The cast spoke after one of the producers, Rory Aitken, said the remake is “clearly not appropriate for younger children”. Stars of the BBC’s new Watership Down adaptation have revealed their performances were shaped by the “terror” they felt as children watching the classic 1978 version.James McAvoy, John Boyega, Gemma Arterton and Nicholas Hoult recalled the traumatic scenes from the cartoon ahead of the new television mini-series which airs this Christmas.The TV remake of Richard Adams’ classic children’s novel, which has sold more than 50 million copies since its release in 1972, uses the latest animation technology to recreate many of the violent scenes which viewers found so affecting in the earlier version.Asked why he took the role, McAvoy, 39, who plays Hazel, said: “From the deep love and terror that watching the 1978 animation put inside my bones, and then from reading the novel later in life when it blew me away all over again.”Arterton, 32, who plays Clover, added: “I remember seeing the 1978 animation when I was very young – and being petrified by it. Having revisited the story as an adult, it’s so pertinent, especially for these days and these times.”The adaptation, which has an all-British cast, will air as two feature-length episodes on BBC One on December 22 and 23. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.