However, if the special proves popular with audiences, a full series could follow.
BAFTA-winner Jason Watkins (Trollied) is to star in the programme as Mr Humphries, the camp character made famous by John Inman. Sherrie Hewson (Benidorm) will take over as Mollie Sugden's Mrs Slocombe.
New characters - Miss Croft, named in tribute to the comedy's co-creator, writer, director and producer, David Croft; and Mr Conway - will be played by Jorgie Porter and newcomer Kayode Ewumi, respectively.
The core cast will be rounded off by Niky Wardley, who plays Miss Brahms; John Challis as Captain Peacock; Roy Barraclough as Mr Grainger; and Arthur Smith as caretaker Mr Harman. Mathew Horne is to play a new Young Mr Grace, grandson of the original Young Mr Grace.
The BBC say: "It's 1988 and Young Mr Grace is determined to drag Grace Brothers into, well 1988, but he has a problem on his hands.
"Mr Humphries, Captain Peacock, Mr Rumbold and Mrs Slocombe all seem to be stuck in another era. A new member of staff, Mr Conway, joins the team but will he help shake things up or will he just put a pussy amongst the pigeons?"
Comedy commissioner Shane Allen says: "The Are You Being Served? special is a riot of a script from Derren and has attracted a real comedy pedigree cast to pay homage to this glorious and much-loved show."
Derren Litten adds: "Writing a new episode of Are You Being Served? has been the most fun I have ever had as a professional writer. We have an amazing cast, a brilliant producer and a great director, it was just too exciting an opportunity to pass up; and I am unanimous in that."
Fans of the comedy will note that the new episode appears to mix various different eras of the long-running sitcom.
Running for 10 series from a 1972 pilot to its final outing in 1985, Are You Being Served? went through a number of cast changes. Notably in relation to the new casting details revealed today, Mr Grainger left in 1977's Series 5.
Additionally, a sequel to the original series was produced in the early 1990s. Running for two series, Grace & Favour saw the main characters set about running a country hotel after an unwise investment of their pension fund by the original Young Mr Grace. It is not yet clear if the chronology of the new 1988-set revival will respect the characters' 1990s futures as established by the original writers, or ignore them.