Even the liberal-minded Polly Toynbee wrote recently that Barnardo's is past its sell-by date, existing just to exist. It has its heritage - indeed, it is planning to open a Heritage Centre - but this longevity almost works against it. It runs community centres, day centres, family centres, training centres. And yet Barnardo's seems de-centred: the centre has not held Other agencies do this work as well.

Devoid of its homes, its boarding-schools for the underclass, Barnardo's lacks a "USP", a unique selling point, to seduce the public. These days the bulk of Barnardo's work is preventive, and not with individual children but (in the hope of keeping them together) with families. Drawing on a budget of pounds 76.5m (half of it from central or local government, half from public donations), its 150 projects (involving 22,000 clients) tackle poverty, drug addiction, homelessness, Aids, disability, juvenile offending and much besides. Six out of 10 adults, asked what they think it does, say that it runs homes for children. But since 1945, with the creation of a welfare state, most of that work has been taken over by local authorities, and the last of the traditional homes closed in the Seventies. We look at the images, and words come rushing to our lips: orphans, urchins, strays, waifs, bastards, vagabonds, gutter boys, street arabs But these are old words, old images.

For an organisation which wants to show that it has entered the modern world, the richness of its archive is a mixed blessing.BARNARDO'S, in other words, has an image problem. The early photographs are so stunning to look at that they have fixed the notion of Barnardo in the national consciousness. Roy grieves that, in a move of offices c1955, all but a handful of the original glass plates were disposed of. Luckily, the prints in albums survived, and he retrieved them from a boiler room in the basement. There are gaps - group photos from 1905-1927, and individual ones after 1939, when Stepney was evacuated - but no other institution in the country has such a well-documented visual history.This success has brought its problems, though. In fact, there have been only five heads of department in 121 years. This knowledge, it is now accepted, is integral to a child's sense of identity: better to know something of one's past, however distressing, than be a child of no one from nowhere.

A fresh start doesn't mean, as Barnardo thought it must, an empty page.John Kirkham is proud of his archive He has been here 14 years His predecessor, Roy Ainsworth, was here for 39. For it is a principle of modern childcare - especially since the Sixties - that children who have been adopted or fostered or placed in local authority care need to know about their past, not repress it. These days such children are encouraged to create "Life Storybooks", to know who their parents were, and to see photographs of what Before looked like. For Barnardo, each child was a tabula rasa, on which he - "the father of nobody's children" - could write his signature.It's this philosophy, more than any other, that now seems most unpalatable about Dr Barnardo. Being snapped was an initiation ceremony in which the child shed its old identity and took on a new one, never to look back again.