Seen it yet? It's on CBeebies at five-twenty p.m., Monday to Friday. It's also out this week on DVD (released yesterday) and it's a cracker. What's not to like about James Bolam in the starring role? I don't know if James Bolam really is a grandfather, but if he's not he ought to be. Artistically - with a career that began in the 1960s and spans a huge variety of theatre and TV roles - he's certainly granddaddy to the newcomer Jay Ruckley who plays his grandson Jason Mason in the programme.
The relationship between grandparents and grandchildren is often special. Spared the role of full-time fall-guy and with a lifetime of experience to draw on, some grandparents find they have more fun with their grandchildren than they had with their own children. And, as the saying goes, at the end of the day they can always shut the door and say goodbye.
But Jason Mason's Grandpa can't. Because Grandpa (Bolam) lives with the Mason family in Sunnysands. And that's something else I love about the series. It's as sunny as a seaside picture-postcard. Ok, bad stuff sometimes happens - often when Great Aunt Loretta (Susan Jameson) comes to stay - but there's always a happy ending, usually resulting from the 'teamwork' of Jason and his incredibly shrinking Grandpa.
Something similar used to feature in The Dandy a very long time ago (if anybody remembers Peter Pocket's Grandpa) but that wasn't set in an idyllic seaside location (Southwold in Suffolk, as well as parts of South Wales were used as the locations). Nor did it have James Bolam as the Grandpa. But the basic idea of a grandfather with magical powers is similar. When Grandpa Mason dons his shrinking cap - and everyone assumes he's gone for a lie-down - he actually gets a brand-new new lease of life and energy, as well as the power to drive toy cars and fly model aeroplanes.
There is a charming, slightly old-fashioned atmosphere about the series as well as real feel-good factor. When it first aired at the crucial tea-time 'meltdown' time last year, it set my remote-control finger twitching over the 'off' button. I was convinced that Charlie would struggle with the ten-minute narrative and fail to identify with the older characters. Not a bit of it! 'Bobba in my poh-ee' is now a firm teatime favourite in our house.
And the fact that it attracts an ever-growing list of guest-stars (Rula Lenska, Geoffrey Palmer, Meera Syal and Liza Goddard to name a few) is proof of its huge popularity.
It's on again today, so as Grandpa Bolam almost says:
"Catch it if you can!"