Emma, BBC One

There’ll always be Austen on the telly. As the Bard is to the boards, so is Saint Jane to the box. The six novels were published (though not all written) in a seven-year period in the 1810s. In a rather shorter tranche of the 1990s they were all adapted for the (mostly small) screen. They’ve now just been done again, on the whole rather less well than the first time round.

And such is the public’s greed for stories from Austen’s world of box-hedged romantic decorum that these days even the authoress gets pressganged into starring as herself. Her early life was covered in Becoming Jane, her later life in Miss Austen Regrets. But for unabashed exploitation on the brand, I have a soft spot for Lost in Austen, ITV’s escapist piece of time-travelling nonsense. Meanwhile, once more unto Mr Knightley's breeches comes Emma.

When Jane Austen talked of creating a heroine "whom no one but myself will much like", she meant Emma Woodhouse. If you actually count Miss Woodhouse’s screen credits it turns out she’s liked more than any of her shelf mates, including the adorable Miss Bennet. Unlike other Austen girls’ troubles, her journey towards wisdom and humility – her character arc, as they say in script meetings – will never age. Not all young girls are hunters of wealthy husbands any more. They do all have to learn to grow up.

As her creator intuited, you should sort of quietly hate Emma as she goes about her match-making business. But each actress has to find a new way to make her unlikeable, or what would be the point? In a double booking of adaptations in 1996, Gwyneth Paltrow invested her with a cold blast of Hollywood hoity-toitiness, while on television Kate Beckinsale was every inch the pouty public-school miss. This time round, Romola Garai plays Miss Woodhouse wreathed in the widest smiles and sporting the biggest bluest eyes. A bushy-tailed Emma for the Facebook generation, she collects friends like a social networker, and uses them for her sport. By the end of part one it had all worked a treat: Garai is never not nice to look at, but I couldn’t stand the sight of her Emma.

The thankless task of extracting something new from a well-thumbed story falls to Sandy Welch, who has adapted Charlotte Brontë and Mrs Gaskell but never Austen. She takes the courageous decision to give a voiceover to Mr Knightley, the second most tight-arsed and uncharismatic hero in all of Jane after that boring vicar in Mansfield Park. Pity poor Jonny Lee Miller: he’s now played both of them. Some kind of penance for having been sinfully convincing as plain Jane's contemporary Byron? It doesn’t feel like Miller’s fault that the barney between Knightley and Emma which closes the first episode lacks the spirit of that fiery encounter between Mr Darcy and Lizzie Bennet. When these two do end up in the marital sack, it’s hard to suppose that they’ll have much fun.

But Welch’s braver choice still is to reconfigure the narrative with a back story. Alan Bleasdale did this once with Oliver Twist, but then that’s a pig’s ear of a plot from when Dickens was still learning to tell stories in monthly instalments. Does Emma really need a flashback to the death of the heroine’s mother, which also makes much of a connection with two other characters’ unhappier childhoods? “Jane, Frank and I are bound together in some mysterious way,” Emma explains. Not entirely convinced that clunking signpost came from Austen's quill.

What Welch succeeds in hinting is that a dead mother and a weak-willed father create perfect laboratory conditions for Emma’s meddlesome precocity. She has no one to put her in her place. The story allows her a companion, albeit not one who actually speaks. Jodhi May gurns and grins and gets married before the script, about 15 minutes in, gives her a line to say. It’s possible Welch hopes to convey Emma’s taste for domination, but it seems harsh treatment for such a fine actress.

Does it matter that one or two of Garai’s frocks are none too Empire-line, or that there’s little of Austen left in the mouths of her characters? There’s no reason why it should. Any Emma will stand and fall on the moment the heroine comes face to face with her unkindness. That's not for an episode or two although, thanks to television’s hunger for a climax, at the end of this opener she has a premature inkling of the blinding flash to come.

If you want the real thing, pick up a Penguin. In the mean time, hats off to the casting director for ticking the boxes. The curate Mr Elton needs to make your flesh creep, and Blake Ritson (who also played the boring vicar in Mansfield Park not so long ago) is tremulously slimy. Miss Bates’s logorrhoea should almost keep a lid on a great reservoir of loneliness, and of course Tamsin Greig does all that stuff to a T. Perhaps Mr Woodhouse, Emma’s neurotic old dad, should be slightly more feeble than Michael Gambon. But then I’d happily watch him as the manipulative Miss Woodhouse herself.