And sure enough, in a set-up that has already been dubbed "the least funny comedy in recent memory" on television, McKellen and Jacobi spend half an hour screeching at each other, waving their arms around, ogling the new upstairs neighbour (played with unbelievable wide-eyed incredulity, and a Rochdale accent, by Iwan Rheon) while ministered to by Frances de la Tour as a dreary old fag hag called Violet.
In terms of breakthrough material, it makes Larry ("Shut that door") Grayson of The Generation Game and John ("I'm free") Inman of Are You Being Served look like flag-waving pioneers for Gay Lib.
They've been together now for 48 years, these two, one a failed actor from Wigan (McKellen) who spent a year in The Mousetrap, the other a sometime barman from Leytonstone (Jacobi) who hasn't yet told his mother about their living arrangements and who keeps bursting into tears at the slightest dig or put-down.
At every point the writing is fatuously unconvincing. McKellen, for instance, picks up a previously unopened letter of admiration from the man whose funeral they've just attended. He reads it, gloatingly, before Jacobi points out it's addressed to him, and that Clive - who was married and had six children - therefore adored the "quiet" one. How many unopened letters do you keep on your sideboard? And for how many years?
They are joined at the wake in their Covent Garden flat by Marcia Warren as a vague biddy who keeps falling asleep with her eyes open (you can hardly blame her) and Philip Voss as a bombastic stingy-boots who complains about the biscuits and the size of Jacobi's finger food.
I suppose you have to acknowledge something about nerve - not bravery, surely - in putting out a sitcom with these gay characters anyway, however tedious and stereotyped they are. But Charles Dyer's Staircase, a 1966 play later filmed with Rex Harrison and Richard Burton as two camp old hairdressers, was infinitely and resoundingly superior.
The trouble with Vicious is that every line tries to be funny (and usually fails) so the energy level of performance is just wearingly the same and decreasingly proportionate to the tsunami of canned laughter that greets each put-down as though it had been written by Oscar Wilde or Simon Cowell. Maggie Smith has the same sort of problem in Downton Abbey.
Two well-known theatrical couples, both known as "The Boys," spring to mind: the delightful theatre historians Raymond Mander and Joe Mitchenson, two former small-time actors who kept a house full of memorabilia in south London and finished each others' sentences rather like Bobchinsky and Dobchinsky in The Government Inspector; and the statuesquely contrasted pair of the flamboyant actor Micheal Macliammoir and the gentle, reflective theatre director Hilton Edwards.
I quite see how Vicious is aiming much lower deliberately in its portrayal of a suburban equivalent of these great couples. But it achieves this target with unseemly haste and will probably just boomerang back to base as an attempt to liven up the airwaves with something grown-up and hilarious about gay domestic life.
I caught the programme on ITV player when I got home from the second revival at the ENO of Jonathan Miller's superb production of La boheme, which is set in 1930s Paris and uses the photography of George Brassai as a visual touchstone. As in all his best productions, Miller makes this "update" work at every level, and there is no hint of strain or awkwardness in the staging.
Kate Valentine may look a little too healthy as the consumptive Mimi, but she acts and sings beautifully, and the Californian soprano Angel Blue makes a glorious ENO debut as Musetta; how she hasn't actually swallowed Simon Butteriss's fussing, funny Alcindoro whole I shall never know.
The band is on terrific form under Oleg Caetani, and Amanda Holden's translation, though a bit over-anxious to rhyme all the time, is a positive pleasure. Not so much vicious, as wicked, man.