Rowan, Tony Robinson, Hugh Laurie, Stephen Fry, Tim McInnerny and Rik Mayall all starred in the hit BBC sitcom written by Richard Curtis and Ben Elton, which followed character Edmund Blackadder through out the ages.
John told The Sun: "Rowan and I had this great idea, because we are all getting a bit old, of doing a kind of Dad's Army.
"They are a platoon in Walmington-on-Sea where they get kidnapped by a German submarine and taken to Colditz. They then have to escape.
"Because Tony Robinson is probably very near 70 now he would be just about the right age. We'd do it as a Blackadder - it would make a good movie, I think."
Blackadder ran on television from 1983 to 1989, with series set in the Middle Ages, the Elizabethan and Regency periods, the First World War and a Christmas special set in Dickensian times. They also made a Millennium special Blackadder: Back And Forth in 1999, which saw the characters travel back to the prehistoric era and into the future.
Tony, 66, played Blackadder's hapless sidekick Baldrick, known for his catchphrase "I have a cunning plan".
He said in 2011 he was keen to reprise the role in a movie spin-off.