WE may not be in the same league as Mike Yarwood – ask your dad – but, if pressed, most of us can pull off a couple of impressions.

For example, after a couple of port and lemons my friend Vanessa makes a fair stab at Joan Greenwood – ask your grandad – and, pardon my blushes, I can do a passable Maggie Smith and bring my repertoire to a spectacular close with one line from I, Claudius – “Let all the p-p-p-poisons that lurk in the mud hatch out.”

Believe me, if you heard it you’d think Derek Jacobi was in the room.

The everyday tale of a despotic, dysfunctional, increasingly insane family who just happened to rule most of the known world, I, Claudius (or I, Clavdivs as we fondly remember it) is one of the jewels in BBC drama’s crown.

Essentially Succession in togas with higher stakes, it was first screened in 1976 and is currently being repeated on that new-fangled but constantly under-threat BBC Four. And what a treat it continues to be!

The Covid lockdown was decidedly short of plus points but for me there was one – boredom eventually drove me into the loft for a much-postponed tidy-up. I felt like Howard Carter up there, unearthing “wonderful things” I’d forgotten we had. Included among them was a box of DVDs, and included among them – stay with me – was a couple of what I believe are called “box sets” – Rome and I, Claudius.

Rome was a high-budget, high-concept HBO series that looked like, and indeed was, a Cinecittà epic. I, Claudius, on the other hand, was a bargain-basement 1970s BBC effort that looked like it was filmed in a garden centre. The latter more or less carried on from where the former left off so we watched them in quick succession.

Rome is pretty good but for all its dollars, gloss and polish it couldn’t hold a guttering flambeau to its pound-shop companion piece, Claudius. As soon as its peerless cast started delivering Jack Pullman’s exemplary script all reservations about its ambient Acorn Antiques sets evaporated.

A quite brilliant interpretation of the Robert Graves novels – he integrated the sequel Claudius The God into his TV version – Pullman cheerfully blended the mundane with the downright bizarre.

In bringing the imperial family to life, he and director Herbert Wise were aided by an equally brilliant cast. Less booming than usual, Brian Blessed made a curiously sympathetic Augustus; more hairy than usual, Patrick Stewart made a manipulative Sejanus. Sian Phillips was a gloriously calculating Livia and John Hurt a chillingly bonkers Caligula. The cherishable performances, however, are legion. Let’s not forget George Baker’s festering Tiberius, Sheila White’s lascivious Messalina or Biggins’ Nero! Then, as historian Natalie Haynes pointed out after a recent revisit, “my favourite thing BY FAR has been the discovery that Patricia Quinn played Livilla. She’s a feckless femme fatale (and patsy to Graves’ monstrous version of Livia).”

Incidentally, Ms Haynes shamelessly plugged an upcoming episode of her Stand Up For the Classics Radio 4 series in which she promises “a more nuanced depiction of Livia”.

If you’re a stranger to the quondam comic’s series, may I steer you in the direction of the BBC’s Sounds app? All the episodes are on there and the Stone Blind author’s a dab-hand at demystifying the ancient world, often using the I, Claudius cast to put flesh on the bones of dusty, long-forgotten figures.

Yes, the entire Claudius cast is first rate. But the fulcrum of the series, the planet around which all these moons orbit, was West Hampstead’s own Derek Jacobi.

Odd thing, telly. An actor can be a huge name at the National and effortlessly pull in the punters in the West End but they can shop in Aldi unmolested; one popular TV series and he or she can never take the tube again. Jacobi is a case in point: a hugely experienced and much-venerated stage actor, he only became a household name after playing the lame, stammering nascent emperor. Such is his identification with the role, it’s now hard to believe his was not the first name in the frame. Perhaps Ronnie Barker or Peter Sellers may have made a decent fist of it, but Charlton Heston?!

Eagle-eyed viewers may have noticed that the BBC series was made in collaboration with London Films, Alexander Korda’s production company that gave us The Scarlet Pimpernel and The Private Life of Henry VIII in the 1930s.

London Films was involved in the Corporation’s version because they held the rights to the Graves novels. As the 1965 documentary The Epic that Never Was explains, Korda had planned to make a film of the books starring Charles Laughton in the title role. Emlyn Williams was to have been Caligula, Flora Robson Livia and Merle Oberon Messalina. Alas, it was a troubled project and production was eventually halted. The remaining fragments of the Josef Von Sternberg-directed extravaganza hint at an unrealised gem.

But hey! Now you younger fry know iClaudius is not an Apple product, you can now head over to the iPlayer and wallow in some quality telly. Saluté!

• I, Claudius is available on iPlayer and being screened on BBC Four on Wednesday at 10.45pm.