"Animals almost beneath contempt" was how one early 20th century Fleet Street editor described newspaper photographers. Today, the significance of photographs in changing and documenting history, in pinpointing the moments when new celebrities and public figures dropped into our collective imaginations, and most significantly, in selling papers - is universally understood.

As it moves chronologically through the political, social, fashion and scandal milestones, 1904-86, the National Portrait Gallery's captivating exhibition of black and white images reveals how photographs have preserved key historical moments more strongly in the collective memory than the written accounts.

Gallery: Daily Encounters: Photographs from Fleet Street

Interestingly, the curator, Roger Hargreaves, book-ends the exhibition with three iconic victims of their day: Christine Keeler and Mandy Rice-Davies at the Old Bailey-during the Profumo case (1963), framed by a pack of flash-toting snappers, and Lady Diana Spencer (aged 19) outside her flat, trapped in a lens for eternity.

Both images established these women in our minds and set their mythic status. The wall of Profumo affair images is a bitter reminder of a morality tale which destroyed careers and lives.

Key paparazzi shots inevitably thread the show - from the innocent picture of the "real" Charlie Chaplin strolling the Embankment to the flash of Edward VII and Mrs Simpson in Venice, which exposed their relationship to the world.

Hollywood's control over celebrities through press conferences is illustrated in the Fifties shoot with Merle Oberon at the Savoy, facing photographers wearing suits and ties. More sophisticated manipulations of truth were the " negotiated portraits", set-ups requiring collusion from the subject and offering fun: such as Alfred Hitchcock, posing, with an expression of mock horror, next to an Evening Standard hoarding that declares "Another necktie strangling".

More serious exercises in imagebuilding are illustrated by Churchill's visits to war-time bombsites, and King George in a trench on the Somme.

A engrossing show, Daily Encounters nonetheless prompts thoughts of what's missing from these snapshots of story. Perhaps the NPG could make a habit of it and put on regular follow-up exhibitions of newspaper photography? My favourite in this display is of two young office workers in a coffee bar in 1953, lost in their newspapers.

• Until 21 October. Information: 020 306 0055