Back review – Mitchell and Webb's return is well worth the wait

They met in Footlights, at the University of Cambridge, of course, but it was Peep Show that cemented the partnership of David Mitchell and Robert Webb. Like many flat-sharers in this economy, they have been more or less trapped together ever since, regardless of any growing resentments. Some sketch shows followed, some books, a badly reviewed stage tour and a reportedly lucrative Apple ad campaign. However, it is only with Back (Channel 4), the Simon Blackwell-penned sitcom-of-sorts now starting its second series, that this duo’s true comedic greatness seems fully realised.

The four-year wait between series necessitates a quick refresher of Back’s thriller-like plot: Stephen (Mitchell) is a defeated sort of man whose brief hope of escaping the shadow of his dead father was snatched away when long-lost foster brother Andrew (Webb) turned up at the funeral. Andrew seemed easy-going, self-assured and adventurous – everything Stephen wasn’t – and was thus poised to usurp him as new landlord of the family’s pub. Their (possibly one-sided) rivalry drove Stephen to madness, while at the end of the series, the fundamental question – is Andrew evil? – still hung teasingly in the balance.

Series two opens with a role reversal. It’s now Andrew who is an under-appreciated fixture behind the bar at the John Barleycorn and Stephen who is “back” after a long absence. He is about to be discharged from Lyneham Abbey Wellness Centre and is, as he tells his credulous therapist, “a very different guy from the one who was forcibly encouraged by his family and the wider community to become a patient here”.

Stephen may have recovered his sanity (debatable), but his nearest and dearest are as enjoyably maddening as ever, with any one of them capable of single-handedly carrying a lesser show. There’s Stephen’s floaty, sexually liberated mother Ellen (Penny Downie), who has started shagging the much younger parish vicar (John MacMillan) and remains vague about the identity of Stephen’s biological father, and anarchic Uncle Geoff (Geoffrey McGivern), who is still railing against health and safety culture, one recklessly stubbed-out cigarette at a time. Stephen’s competitively neurotic sister Cass (Louise Brealey) is also hanging around to question why Stephen got therapy when, “I’ve always been the one with so much mental complexity going on.”

Yet only the infuriatingly calm Andrew retains the ability to really get under Stephen’s skin. He wants to apologise for “everything” that happened before. “Everything in the world?” Stephen snaps back. “The Napoleonic wars? The cry-laugh emoji? Slavery?” Andrew’s response is a masterclass in non-apology-apology, all passively constructed sentences and put-on empathy. It is a chilling hint at the monster Peep Show’s Jeremy might have become, if only his gnat-like attention span had allowed him to read past the opening page of a psychology textbook.

Their pissing contest takes place, appropriately enough, by the pub urinals. Indeed, it’s the middling provincial pub – that last refuge for broken British masculinity – which is the true star of Back. This was also the case in series one, but it has been thrown into sharper relief by the opening of a rival down the road, the unpronounceably named P:ub. While staunch traditionalists such as Stephen may scoff (“You don’t want to reference colons if you’re serving food”), others have already proved themselves susceptible to the glib charms of pretentious newcomers. The bar staff seem particularly impressed by P:ub’s minimalist menu, offering such dishes as “stove-warmed fish”, “leaves” and “local curds”.

Related: Back review: farewell to Mitchell and Webb’s squirmingly good sitcom-cum-thriller

In setting and ambiance, Back is as drearily British as Brexit, but its densely packed dialogue – roughly every third word is hilarious – ensures it is also recognisably kin to glossy American cousins such as Succession (written by Blackwell’s old collaborator Jesse Armstrong) and Veep (on which Blackwell has writer and executive producer credits), all of which can be traced back to a common ancestor in Armando Iannucci’s The Thick of It. It is only Back’s characters that are contentedly parochial, everything else about this show is world class.

It will take at least until the end of this six-episode run – and hopefully a few series more – to discover whether either Andrew or Stephen can really change. But since sitcoms are shows about people who never do, and since Mitchell and Webb have been playing out slight variations on the same gloriously dysfunctional dynamic since 2003, that seems unlikely. It is a testament to the masterful construction of this comedy-thriller that it remains possible to imagine they might. Let the mind games commence.