This month’s Sunday night viewing wars have given us a heroic clash of mettle on mettle. While most viewers sided with BBC1’s Bodyguard, I’ve pinned my colours to ITV’s adaptation of Vanity Fair.

Both are masterclasses in sexual politics, but whereas Jed Mercurio’s pairing of a lonely home secretary with her physically and psychologically scarred minder led us up an implausible cul-de-sac, William Thackeray commands the heights of social satire with a story that, to co-opt one of his most famous pronouncements, “gives back to every era the reflection of its own face”.

It’s a familiar complaint that no film or TV version can live up to the novel, because none can be so unremittingly nasty. But before dismissing this latest adaptation, it is worth bearing in mind the less familiar second part of that mirror quote: “Frown at it and it will in turn look sourly upon you; laugh at it and with it, and it is a jolly kind companion.” Ever since Chester M Franklin’s expressionist 1932 version brought Vanity Fair into the age of the talkies, with Myrna Loy as a hollow-eyed casino hustler bound for a tragic end, interpretations have lined up along the spectrum this quote suggests.

The tone is always set by Becky Sharp herself, who has become increasingly impossible to caricature over the decades, as a low-born orphan battling the disadvantages of class and gender. The more extreme the scenario, the harder it is for an actor to get their claws into the role – witness Reese Witherspoon, left with nowhere to go but nice, against the flamboyant colonial ghastliness of Mira Nair and Julian Fellowes’ 2004 movie version.

‘Nowhere to go but nice …’ Reese Witherspoon as Becky Sharp in the 2004 version of Vanity Fair. Photograph: Focus Features

Writer Gwyneth Hughes gets round this by emphasising the illusory nature of the story, as did Thackeray himself, opening each episode with a top-hatted Michael Palin directing the revolutions of a gilded merry-go-round. It is a different sort of textual faithfulness than the usual deployment of the costume department’s finest regimental scarlets to the mustering scenes, although this series does that too. It is a faithfulness to Thackeray’s tone, to his direct address to the reader, which draws us into complicity with his God’s-eye view of the human comedy.

Awareness of this artifice is kept going with knowing camera work: Olivia Cooke’s Becky might be as fresh-faced and charismatic as they come, but she stands apart from her companions in being allowed regularly to break the fourth wall with conspiratorial glances. The key early encounters with the snobbish parents of her schoolfriend, Amelia, set up a double irony as she is stared down by Sam, the Sedleys’ black servant.

Richie Campbell’s Sam is a revelation: a proud and contemptuous figure who slips across the background of a scene in which Becky boasts to her new friends that her mother was a Montmorency. He also usurps her first attempt to entrap the tubby Collector of Boggley Wollah, by bursting into the room with a towering gateau.

In true Thackeray style, the more ridiculous a character, the more odious their hypocrisies. David Fynn’s sneezing and stammering Jos Sedley is on the verge of becoming the pitiable victim of Becky’s wiles when his social floundering inflates into drunken monstrosity. It gets worse when Becky is exiled to the rundown Pitt Crawley mansion, where she faces down the advances of Martin Clunes’s gurning Worzel Gummidge of a baronet and the bossy pieties of his son and daughter-in-law, only to find herself enveloped in the toxic confidence of the vicious Aunt Matilda, who is gloriously played by Frances de la Tour as a gleefully vicious toad in a mobcap. Perhaps she’s a warning of what Becky might become, given too much of the worldly power she so desires.

Martin Clunes as Sir Pitt. Photograph: ITV

All comic grotesques need their stooges – and this is the hardest position to hold in such a vicious satire. After a queasy initial backstairs encounter, the romance between Becky and Tom Bateman’s Rawdon is played pretty straight: here, it’s clear, is a match both of libidos and lusts for life. As such it’s in counterpoint to the peevish alliance of Claudia Jessie’s fluttery Amelia and Charlie Rowe’s puppyish George, whose ardour seems as limp as the bouquet he thrusts at Becky as battle looms on the night of the regimental ball in Belgium. (Bouquets, rather wonderfully, seem to be enacting a shadow drama of their own in the first four episodes.)

Where, quite, this all leaves Dobbin, the faithful friend and constant lover, remains to be seen. Johnny Flynn doesn’t aspire to the the bruised charisma of Philip Glenister in the 1998 BBC mini-series (scripted by Andrew Davies). So far, he’s a colourless character, whose occasional clumsiness seems incidental rather than a defining – and endearing – trait. Perhaps it’s not the social climbing woman, but the honourable man who has a hard time finding his reflection in the mirror of the current era. But Dobbin has another two episodes in which to press his suit and we shall all just have to wait and see.