When his family can no longer look after him he is moved to an old people’s home called Twilight Towers, run by Miss Dandy.
It soon becomes clear that Miss Dandy (Jennifer Saunders) is running Twilight Towers for her own ulterior motives, and it is up to Grandpa, played by Tom Courtenay, and his grandson Jack (Kit Connor) to make a daring escape.
Failure could have the most dire consequences, but success will give Grandpa a final chance to relive his past – and once again take to the sky in his beloved Spitfire.
Running throughout is Walliams’ trademark wit and this should be one of the highlights of this year’s festive TV schedule.
Walliams told the Radio Times: “The book was actually inspired by a news story about a guy called Bernard who escaped from an old people’s home to go to Normandy for a reunion with his Army colleagues.
“I am thrilled to be working with acting and comedy royalty on this adaptation of my book. I have loved Tom Courtenay forever and I still can’t believe that I am working with him. He is the perfect Grandpa. And what a treat to be working with comedy genius Jennifer Saunders again.”
Grandpa’s Great Escape, New Year’s Day, BBC1, 6.55pm