Mariah Carey talks about her love of all things Christmas, Gary Barlow says Take That showed him how to be young, Nadiya Hussain believes Bake Off winner Peter is in for quite a ride, Tim Peake says he is waiting by the phone for his next space mission, and Richard Osman talks about the Britishness of his new book.

Mariah Carey, joining Graham from LA for a chat about her Magical Christmas Special TV show, says, "It's going to be festive. Everything I put my heart and soul into will be festive. It's been such a tough year for everyone, but in no universe will Christmas be cancelled for me, so we are doing this special. People will really get into the Christmas spirit with it and it is something we all need this year."

Revealing her love of fabulous Christmases is because they weren't so fabulous when she was young, she says, "I always wanted them to be great as a kid, but they were somehow always foiled by other people when I was growing up. I didn't grow up with money or things, but I always loved Christmas but certain people or siblings, who I don't know any more, would come over and ruin it every time. So, as an adult they will never do that to me again."

And, on her hit song All I Want For Christmas Is You, she says, "It was the first Christmas song I ever wrote and then it took on a life of its own. I loved it for me, but as the years went by other people liked it and I've grown to love it more and more."

Gary Barlow, talking about the inspiration behind his new album Music Played By Humans, says, "It's the type of songs and music I grew up with. My dad used to play a lot of Frank Sinatra and Sammy Davis Jr., so that sound was in our house a lot. It's been one of those albums where you don't have to follow the rules of pop music - I didn't try and simplify it at all and what I wrote, I left in. When you go into places like Abbey Road and there are 60 people playing your music it's just utterly thrilling."

Asked about his early career, he says, "I got my first gig when I was 11 so by the time I joined the group [Take That] I'd done thousands of shows and I just used to walk on stage as though I was going into the living room."

Talking more about growing up surrounded by adults, he says, "When we did the Take That audition, I knew I could sing well but when the other guys arrived, they looked so cool - they were dressed like 19 year-olds and I came dressed as a magician! I couldn't do any of the moves and I really felt on the back foot. Luckily, I could sing, and they could dance so we shared skills, and they showed me how to be a 19-year-old!"

Nadiya Hussain, talking about her new book and TV series Nadiya Bakes, says: "It was important to me after Bake Off to cement myself in a kitchen where I am happiest and when I wrote my first book it was all about cookery. A baking book has been a long time coming, and it's one of the best things I have ever done because five years later, it feels really important to me to do a baking book and feel I am comfortable in my industry now."

Talking about the recent series of Bake Off and Peter's win, Nadiya says, "He's in for quite a ride. It is such a bizarre experience because there is a naivety to filming something like that because you are so immersed and focused on baking you forget that there are millions of people watching you. You walk out and you think, 'How do they know me?' But he will love it. It's great."

Tim Peake, talking about his autobiography Limitless, says: "It's really the journey from young boy to astronaut. I feel a bit of a fraud because as a boy I had no ambitions at all of wanting to be an astronaut - I was obsessed with being a pilot."

Asked by Gary if he was scared going into space, Tim says, "There is always a thought at the back of my mind that I am rolling the dice, but the overriding feeling is of adrenalin fuelled excitement." Adding, "Walking in space feels incredibly exposed and the danger is palpable out there."

Answering another of Gary's questions on whether he would do it again, Tim says, "I'd love to - absolutely. In fact, we are all slated for a second mission between now and 2024. I'm waiting by the phone!"

Revealing he once thought he saw UFOs, he says, "Space is very black and one day I was looking out and there were three lights moving in formation and then there was a fourth. We were perplexed until we realised that what we thought were the far away lights of alien spaceships, were actually very close small droplets. What was happening was liquid leaking out of a Russian probe vehicle, crystallising instantly and reflecting the light. What we were seeing was Russian urine!"

Richard Osman, talking about the success of his debut novel The Thursday Murder Club, says: "I'm very chuffed and surprised. It's a very British murder mystery and inspired by a lifetime of reading crime fiction. I wanted to write a book that I would love to read, and fortunately other people seem to like reading it as well, which is very nice."

Asked about Steven Spielberg picking up the film rights, he says, "I genuinely thought 'What if this isn't any good?' so I wrote it in secret and didn't tell anyone, so the fact that Spielberg, who doesn't watch Pointless or know who I am, read it and said that he loved the characters and loved the story gave me a huge amount of confidence. And, obviously I played hard to get for about nine seconds!"

Talking about the book being published in America, he says "Because it is really very English, I thought it wouldn't sell there but they bought it. The only trouble I had was some of the terminology they didn't understand. They don't really know what Robert Dyas is, or what Sainsbury's Taste The Difference is - and the book is full of that stuff as I didn't hold back on what I know. I did have to change the description of character going for a 'slash' in the woods - it literally blew their minds. They were like, 'Have we missed a plot point here?'"

Gary performs Incredible live in the studio.

And finally, Graham pulls the lever on Richard who volunteers to sit in the Red Chair on behalf of audience members telling their funniest stories from the comfort of their own home.