Jane Austen was in little doubt about the likeability of the eponymous character of her penultimate novel Emma. She was, observed the writer presciently, "a heroine whom no one but myself will much like." Snobbish, vain and meddling, there would indeed seem very little to attract modern audiences to the romantic liaisons of 19th-century Highbury and its cupid-in-chief.
But since the mid-1990s, when TV viewers swooned in their millions at the sight of a clingy-shirted Colin Firth as Mr Darcy in Pride and Prejudice, the costume drama has proved a sure-fire vehicle for popular and critical acclaim on screens both large and small. Interest in Emma also peaked in that decade, when it underwent the Hollywood treatment only a year after the film Clueless transported the classic story to modern-day California. At the same time, Kate Beckinsale gave perhaps the most enduring modern performance in an ITV adaptation.
Yet this week, that once assured success looks in doubt, as BBC bosses were forced to defend their latest lavish interpretation of the book. Starring Romola Garai as Emma, Michael Gambon as her father and Jonny Lee Miller as the love interest Mr Knightley, the second part of the prime-time Sunday-night costume drama pulled in only 3.5 million viewers – down nearly 1 million on the opening episode the previous week – while the third episode saw another 200,000 switch off.
It was trounced in the ratings by ITV1's comedy drama Doc Martin and came in way below its anticipated reach of 5 million viewers. By contrast, Doc Martin saw an extra 600,000 viewers tune in to catch up with the exploits of Martin Clunes as the hemophobic medic last week – good news for the troubled broadcaster, which saw its share of the Sunday prime-time audience reach 33 per cent. A spokeswoman for the BBC said it had no explanation for the ratings dive of its flagship autumn show. "It is not all about ratings. We are happy that the audiences that are watching are really enjoying it," she said.
While the corporation insists that viewers have been telephoning and emailing in sufficient numbers to reassure drama chiefs that the investment – a commercially sensitive secret – was justified, the critics have given it a qualified nod of approval. One theory is that Doc Martin is benefiting from its weekly inheritance of a 13 million-strong audience from ITV1's all-conquering X Factor compared to just 5 million that roll over from the BBC's stately Sunday staple The Antiques Roadshow. But a growing number of others believe the days of bonnet and bustle are over.
Yet Emma's lacklustre ratings have not discouraged the BBC from playing what is widely considered to be one of its ace cards. A two-part Christmas special of Cranford, based on the novellas of Elizabeth Gaskell published between 1849 and 1858, are already scheduled. Then there are 13 episodes for the third series of Lark Rise to Candleford based on Flora Thompson's evocation of mid-Victorian life in the Chilterns.
In January, the BBC indicated it was to start moving away from the 19th century, seeking a grittier and more up-to-date – if equally lavish – direction for its dramatic output. BBC drama commissioner Ben Stephenson envisaged evolution rather than revolution, hardly surprising considering that so-called "bonnet productions" have historically accounted for 15 per cent of the department's output. Evidence of the change came with the announcement of a new adaptation of Andrea Levy's well-received novel Small Island, about immigrants arriving in the UK from the Caribbean in the post-war period. There will also be a Christmas special updating Henry James's late-Victorian ghost story The Turn of the Screw to the 1930s. To complete the foray into the last century, BBC Four is broadcasting a series of one-off dramas based on the lives of three famous British women – Margot Fonteyn, Gracie Fields and Enid Blyton.
The BBC has faced some high-powered criticism in recent weeks. Author Howard Jacobson accused the corporation of being over-reliant on the "moribund" drama of Dickens and Austen while eschewing more modern writers such as Philip Roth and Saul Bellow. Andrew Davies, whose canon of work includes some widely acclaimed reworkings, accused the BBC of plunging "downmarket" for its decision to scrap the development of Anthony Trollope's The Pallisers and Charles Dickens' Dombey and Son in favour of old warhorses such as David Copperfield.
Wet shirts and meddling heroines: Rise of the costume drama
* Benchmark-setting TV mini-series of Pride and Prejudice starring Colin Firth as the wet-shirted Mr Darcy and Jennifer Ehle as Elizabeth Bennet
* Clueless: Vapid Hollywood teen update which took Emma and plonked it down in modern-day California, starring Alicia Silverstone
* Persuasion: BBC film, starring Amanda Root and Ciaran Hinds
* British film version of Sense and Sensibility, directed by Ang Lee and starring Emma Thompson
* Gwyneth Paltrow starred in Hollywood remake of Emma
* Andrew Davies movie screenplay of Emma, for ITV, starring Kate Beckinsale and Mark Strong
* Film version of Mansfield Park, starring Hannah Taylor Gordon
* Critically acclaimed Bleak House, mini-series, starring Charles Dance
* Pride and Prejudice: Oscar-winning film version starring Kiera Knightley
* Persuasion: ITV film starring Sally Hawkins and Rupert Penry-Jones
* Mansfield Park ITV one-off starring Billie Piper
* Becoming Jane: Hollywood milks the legend still further with Anne Hathaway as Jane Austen
* Northanger Abbey: ITV TV movie starring Felicity Jones and JJ Feild
* Cranford: BBC series, Elizabeth Gaskell's tale of Victorian women's lives in the rural North-west
* Sense and Sensibility: BBC drama three-parter written by Andrew Davies
* BBC's first series of Flora Thompson's 19th-century bucolic saga Lark Rise to Candleford
* BBC remake of Oliver Twist
* Jane Eyre: BBC dramatisation of Charlotte Brontë's novel
* Tess of the D'Urbervilles: BBC adaptation of Thomas Hardy's novel
* Dickens again with BBC's Little Dorrit
* Daniel Deronda for the BBC starring Hugh Dancy in George Eliot's last novel
* Wuthering Heights was reprised for ITV's summer schedule
* The latest version of Emma, starring Michael Gambon, Romola Garai and Jonny Lee Miller