'Portraiture is now in the hands of women,' said the eminent photographer HS Mendelssohn in 1903. And he was right. While in 1890 only one woman ran a leading West End photography business, by the turn of the century, many middle-class women had seized the medium as an all-consuming occupation, demonstrating wild flights of imagination, resourcefulness and technical expertise. Julia Margaret Cameron is all too often held up as the shining light of 19th-century photographic portraiture and while her body of work is undoubtedly stunning, it's good to see the NPG showcase the work of four lesser-known, but no less important, pioneers of the medium.

'Edwardian Women Photographers' shows us a wide range of material by Eveleen Myers (1856-1937), Alice Hughes (1857-1939), Christina Broom (1856-1939) and Olive Edis (1876-1955). And while these pictures are marvellously entertaining in themselves, they assume an even greater significance when you consider them in the light of the changing role of women in Edwardian society.

These women, you soon discover, were no shrinking violets: Christina Broom, for instance, was Britain's first woman press photographer who covered the Oxford and Cambridge boat races, historical pageants and Suffragette meetings. Olive Edis (who took the portrait of Thomas Hardy, right), was the only woman granted permission to take documentary photographs of women contributing to the war effort during the First World War in France and Flanders. Slightly less emancipated, perhaps, was Eveleen Myers - a friend and disciple of Julia Margaret Cameron - who concentrated her career on photographing her children, albeit exquisitely and inventively. Alice Hughes, meanwhile, remains one of the most successful photographers of women in the Edwardian era (specialising in society and royalty), allegedly inspiring many other women to take up photography as a career. A credit to the cause.

National Portrait Gallery, St Martin's Place, WC2 (071-306 0055) from Fri to 25 Sept

(Photograph omitted)