Joining Graham: Mariah Carey, promoting 'Mariah Carey's Magical Christmas Special', TV chef and writer Nadiya Hussain, whose new book is'Nadiya Bakes', British astronaut Tim Peake, presenter Richard Osman and singer-songwriter Gary Barlow.
Quest roles:
Gary Barlow(Self), Tim Peake(Self), Nadiya Hussain(Self), Richard Osman(Self), Mariah Carey(Self)