Johnny Depp described his daughter's time in hospital at London's Great Ormond Street as "the darkest period of my life".

Sixteen-year-old Lily-Rose was admitted to the children's hospital for nine days in 2007 for kidney failure caused by E.coli poisoning while Depp was filming at Pinewood Studios.

Speaking to Graham Norton about returning to the hospital to cheer up patients dressed as his Pirates of the Caribbean character Captain Jack Sparrow, Depp said: "For me it's a gift. They give me the gift.

"When my daughter was ill in Great Ormond Street it was the darkest period of my life. I'd always done these visits but after that experience the visits became more and more important.

"The kids are so courageous but to be able to bring a smile or a giggle to the parents means everything in the world to me."

The actor is in London to promote his new film Black Mass in which he plays crime boss James "Whitey" Bulger and joked that he had his eyes set on a knighthood in the capital.

"I end up here quite a lot. I'm after the 'Sir' thing," he said.

But Depp might struggle to understand a ceremony if his first meeting with royalty is anything to go by.

"I met Prince Charles. He came to the premiere of Finding Neverland, I shook his hand but I didn't understand a word he said and I don't think he understood a word I said so it wasn't very meaningful necessarily, but he seemed nice!" he said.

Benedict Cumberbatch stars alongside Depp and joined him on Norton's sofa to discuss his recent fatherhood.

"I've become a father and a husband, and in the right order - just! I might go for a Cumber-batch of boys," he said.

The in-demand actor has a full schedule filming Andy Serkis' Jungle Book: Origins and as Marvel's latest superhero Doctor Strange, but admitted he is "always in a rush to get back" to his son Christopher and wife Sophie.

"I'm always in a rush to get back. It's everything. I have a new life form that needs his father's help in the world and his mother needs a little help once in a while," he said.

Asked about the Sherlock Victorian special, airing on new Year's Day, Cumberbatch confessed not even he had watched the hotly-anticipated episode.

"It's great, it's fantastic, but I haven't actually seen it yet," he said.

Also on the sofa were Victor Frankenstein actors Daniel Radcliffe and James McAvoy, who admitted that filming the gothic horror had caused some marital problems.

"The only place that looked like my laboratory was an old Victorian sewage works that still stank of old Victorian sewage. We were there for five or six days and when I got home from work my wife would make it clear I wasn't to come near her," McAvoy said.

McAvoy also spilt a potential secret from the upcoming X-Men: Apocalypse, where his character Charles Xavier finally goes bald.

"We couldn't have a superhero just lose his hair so he goes through something so horrible and painful that he literally half pulls his hair out and the rest falls out," he revealed.

"Fox Studios that owns me might be angry with me," he said of the plot slip.

Musical entertainment was provided by The Corrs who reunited after a 10-year hiatus.

The Graham Norton Show will air on November 27 at 10.35pm on BBC One.