Grandpa in My Pocket is a comedy drama series commissioned by Michael Carrington for CBeebies, the BBC's dedicated pre-school and nursery channel targeting children aged 1-6 years. The programme stars James Bolam, Jay Ruckley, Josie Cable, Zara Ramm and Sam Ellis. The story centres on Grandpa, who owns a magical Shrinking Cap, which only his grandson Jason knows about. This cap enables him to shrink to about 4 or 5 inches tall and experience many magical adventures which are told via voice-over narration by Jason, including finding a hamster under the floorboards and bringing a home-made robot to life.
When miniaturized, he has enough magic power to make Jason's toy car and toy biplane and toy railway locomotive work as the real vehicles including making engine noise, and drive them. Jason has a simple toy glider made of two pieces of wood in the shape of a seagull which he calls Gordon; Grandpa, when miniaturized, can ride on this and make it fly like a real seagull.
When miniaturized, Grandpa can jump much farther in proportion than in full size, and can also "run for all he's worth", as Jason puts it.
Grandpa is never identified on-screen with a proper name, so we never learn whether he is Mr. Mason or Mrs. Mason's father – both refer to him simply as "Grandpa" in much the same way as the parents of comic strip characters – such as The Beano's Dennis the Menace, for example – call each other "Mum" and "Dad". Even Grandpa's own sister, Great Aunt Loretta, only ever calls him "Grandpa".