A third, hour-long special will be entitled Saucy Nancy.
The producers say: "Mackenzie Crook has written another beautifully crafted and magical episode, inspired by the classic books by Barbara Euphan Todd, which he will direct and star in, bringing a world of adventure to all the family."
Talking about the plot of the new hour-long episode, the producers explain: "When Worzel Gummidge, Susan and John visit a scrapyard, Worzel overhears the grumbling of a foul-mouthed old friend - a carved ship's figurehead, Saucy Nancy. She has been languishing, unsold in the yard for years and longs to return to the sea. Worzel and the kids promise to get her there, but will her ship be waiting? Worzel doubts it, but Nancy is convinced. She can feel it in her carvings.
"Adventure unfurls, as the strange foursome navigate their way to the coast on foot, by bus, wheelbarrow, motorbike and sidecar. It was never going to be straightforward. In a rare trip out of Scatterbrook, Worzel gets to see a wild moorland and the spectacular white cliffs of Seashell that provide the backdrop to this story of friendship and belonging."
Shirley Henderson, who played Jude in the three Bridget Jones films and was Moaning Myrtle in the Harry Potter film series, will take on the role of Saucy Nancy. In the 1979 - 1981 TV version starring Jon Pertwee, Nancy was played by Barbara Windsor.
It has also been announced that multi award-winning actor Vanessa Redgrave will play Peg. Further casting will be announced soon.
As previously reported, British Comedy Guide understands more episodes had been planned, but it would appear due to coronavirus safety restrictions it is only proving possible to film one new episode this year.
Mackenzie Crook says: "I'm excited and grateful to be making a new episode of Worzel Gummidge after a difficult year for everyone. We're heading out of Scatterbrook for this story on a day trip to the seaside, some fresh air and some wide open space."
BBC commissioner Shane Allen, referencing Crook's previous sitcom Detectorists, adds: "What is it with Mackenzie and shows set in a field? Following on from last year's bucolic eco-fables we find Worzel in mischievous form dispensing his sun-baked wit and wisdom in another heartwarming tale. This cements BBC One's unique reputation as the home of UK family comedy drama."
Saucy Nancy will be shown on BBC One at Christmas.
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