This tiny, free exhibition in an NPG nook doesn't bother with the question of whether the world needs to see more pictures of Norma Jeane Mortenson, or indeed, any of the same ones over again. But you might as well ask why we look at any photos, or hire good-looking actors to star in films, or concern ourselves with beauty at all.
We love her, perhaps, because of her combination of innocence and knowingness. The smile is Judy Garland, the eyes Ava Gardner: she's permanently, sweetly unsatisfying, the visual equivalent of the siren's song and possibly just as dangerous.
Some images here are very familiar – André De Dienes's early modelling shots, stills and lobby cards from 'The Prince and the Showgirl'; the swirling white dress above the notorious grating – and some are not. Most notably, the soft-focus, comically romantic image by cinematographer Jack Cardiff that overlooks the exhibition, in which that wonderful face plays peek-a-boo with the monochrome blonde tresses and with our lurid imaginations.
Now you see her, now you don't – except you do, endlessly, especially when she's not there. Marilyn Monroe was a decent actress, a great star and a love object so promiscuous that it's a little cheeky for the NPG to lay claim to her on behalf of the Brits. And as a phantom she's without equal.