Rod Stewart banned a BBC film crew from filming his model railway because it is private despite opening up on screen about his hard-living days and complicated private life.
The 68-year-old singer collaborated with the corporation on a new documentary about his career, called Can't Stop Me Now, which mixes archive footage and interviews with himself and his family.
But he told the Radio Times some things had been off limits - including the railway set at the top of his house.
He said: "There are very few places in my life that I like to keep private: that's one of them, and another is soccer on Sunday morning. We sneak to the location and the team has never given me away. Every three years Model Railroader magazine puts me on their cover, which is better than Rolling Stone."
Rod refused to rule out a reunion with his old band, The Faces, who featured current Rolling Stone Ronnie Wood on guitar.
He said: "Ronnie and I talk about it, and when the Stones finish - Mick Jagger is several years older than me - we'll have a window of opportunity if we're not on zimmers. Keep the faith. I've always looked on myself as one of a band and never sought a solo career."
Rod, who has been married three times, became a grandfather after his daughter, Kimberly, gave birth to Delilah - her daughter with Oscar-winner Benicio del Toro.
The singer praised the actor who he said was 'great and has been generous financially'.
