Witches always come in threes, and gothic spinster sisters too, so an early photograph of three severe looking women must be the Brontë sisters – mustn't it? – especially if the scribble on the back could be read as their pen name, Bell. ‘Relikes been they, as wenen they echoon,’ says Chaucer’s Pardoner; everyone wants to believe in relics and to know what lady novelists looked like (Shakespeare too, but no one seems too fussed by what Smollett or Thackeray looked like, though we have pictures). The photo, bought on eBay for £15 by someone convinced it's of the Brontës, is a collodion positive, the slow process (it takes up to fifteen minutes to develop) which began to replace daguerreotypes in the 1850s, and was itself replaced by gelatin plates not long after. Anne and Emily were both dead by 1850, so to be a picture of the Brontës this would have to be a photograph of an earlier daguerreotype.

There’s no record of them having their picture taken, photography wasn't exactly flourishing in Howarth in the 1840s, and it would have been expensive: their inheritance from Aunt Branwell in 1843 went into York and Midland Railway shares and they lived off the interest. Collodian prints (known as ambrotypes in America, where they were more common) were sometimes made of popular daguerrotypes because daguerreotypes couldn’t be easily reproduced, and collodian prints were cheaper. But there was no commercial incentive to reproduce photographs of the Brontës in the 1850s, when only Charlotte had any renown.

Apart from anything else, it looks nothing like them. When Anne was four she told her father she wanted ‘age and experience’ but the women in the photograph are closer to middle age than the sisters would have been (Anne was 28 when she died). They’re too cross-looking, too - the Brontës weren’t called pretty but were ‘of pleasing appearance’ and would have worn their hair in spaniel curls, defying the likes of Mr Brocklehurst, who in Jane Eyre threatens to have Julia Severn’s naturally curly hair cut off for ‘conforming to the world so openly’. They were too young (and unmarried) to have donned a cap for the occasion like the woman on the far left, and would have worn their finest dresses – a wide-necked gown with a pelerine or collar for modesty perhaps. In the painting by Branwell known as the Gun Group Portrait, of which only one figure remains, they went bare-shouldered, though later engravers added chemisettes.

Charlotte’s husband, Arthur Bell Nicholls (they had been married for less than a year when she died in 1855) destroyed the Gun Portrait, having torn off the one figure he thought a fair likeness. It’s traditionally said to be Emily but based on Branwell’s surviving group portrait and Charlotte’s own sketches looks more like Anne. All the sisters had something of their parents’ aquiline beakiness (we have a definite photograph of Patrick Brontë from 1860 and drawings of Maria) but Anne ‘was quite different in appearance from the others’, according to Ellen Nussey, Charlotte’s friend and correspondent. Her features were finer, she was thinner and her hair was fairer – almost reddish blonde in some drawings. The woman recorded by Branwell and Charlotte, though sometimes exaggerated, is clearly the same person and definitely not the central sitter in the photograph.

For Charlotte and Emily we could do worse than rely on Branwell’s painting, which while no masterpiece doesn’t seek to flatter either – unlike later portraits of Charlotte by George Richmond and J.H. Thompson, the latter probably after her death. A possible later photograph of Charlotte, the one on her Wikipedia page, is disputed and doesn’t look like any of the women in the group portrait either.

A photograph surfaced a few years ago purporting to be of ‘Les soeurs Brontë’ (‘Charlotte’s’ hat was too modern); in 2011 it was claimed that a group portrait by Landseer coming up at auction was of the three. There may still be accidental discoveries to be made – a few years ago the LRB published a previously unknown story by Charlotte, 'L’Ingratitude' – but they are unlikely to be images. The voyeurs, meddlers and exploitative biographers would have flourished them long ago.