Michael Palin admits previous plans for a tour fell apart 15 years ago as the surviving members of the British comedy troupe did not want to continue without their friend, who died from cancer in 1989.
Palin was initially very reluctant to agree to perform without Chapman, but was won over when he realised technology could be used to bring him back to life for the reunion show next summer (14).
He tells Britain's The Sun newspaper, "Part of my reason for not doing a stage show 15 years ago was because we'd miss Graham. He was a vital member of the cast and a brilliant writer. Who else could play the Colonel and do all of those other amazing things Graham did? He was such a distinctive performer that I can't imagine hiring anyone else in his place.
"But this time we haven't had to think about him - and not because we're anti-Graham in any way. The great thing is that we can use technology to bring Graham in and not actually have to replace him. I think in a few of the sketches one of us will play his role, but not too much. He'll be seen and remembered, he's very much part of the show."
John Cleese, Terry Gilliam, Eric Idle, Terry Jones and Palin will perform at London's O2 Arena on 1 July (14).