It is not always easy to grasp what Britain's National Portrait Gallery is for. Is it about fame or the art of portraiture? And, if the former, how to differentiate it from Madame Tussaud's or a historical Hello!? The specification set out in 1856 by the gallery's original proposer and first chairman, the 5th Earl of Stanhope, was clear enough. His Lordship wanted the collection to consist "as far as possible of those persons who are most honourably commemorated in British history as warriors, or as statesmen, or in arts, in literature or in science". Stanhope's plan was adopted by parliament and, in order to ensure no person of more transient fame crept under the wire, a mortality threshold was put in place: unless you were the reigning sovereign, you had to be 10 years dead.
On the face of it, the first 19 acquisitions conformed obediently to Stanhope's parameters. The painting labelled NPG 1 is a national icon, the "Chandos portrait" supposedly of Shakespeare. Attributed to an otherwise obscure London painter, John Taylor, it shows a gypsy-like bard with swarthy looks and a gold earring. The work was presented in December 1856 as a founding acquisition by one of the gallery's first trustees, Lord Ellesmere, and was quickly followed over the next six months by another four writers, seven politicians, four military men, the composer Handel, the Royal Academician Thomas Stothard and the royal physician Richard Mead. Only three of these first 19 exhibits are by major artists: Allan Ramsay's portrait of the inoculation pioneer Mead, a lively Romney portrait of his patron, the once noted playwright Richard Cumberland, and an ambitious but unfinished picture of William Wilberforce by Thomas Lawrence. The rest are doubtfully attributed, or copies, or by painters half-forgotten. So, while the trustees occasionally went for "important" paintings, they did not insist on artistic excellence, and not even on originals. It was the national and historical status of the sitters that impressed them.
Or did it? Suddenly in July 1857, when they accepted NPG 20, they appeared to change direction. This is Elizabeth Grammont, Countess of Hamilton, the first portrait ofa woman to be allowed in. Shewas chiefly noted as one of the glamour-girls of Charles II's court, and this portrait is a copy after Lely, the specialist in court beauties. So the gallery appears, within half a year of its launch, to have abandoned the founding formula and put a 17th-century Spice Girl on the walls, albeit quite a Posh Spice. And nor was she to be an exception. Within two years the Trustees had got hold of a "Nell Gwyn by Lely" (she later turned out to be Catherine Sedley, James II's mistress) and, not long after that, the other Lady Hamilton, Lord Nelson's, was admitted to the fold in a sultry painting by George Romney.
These women were not quite honourably commemorated - certainly not by the Victorians of the 1850s - but they were celebritiesall right, and they had pulling power. This is of course the nub of the issue, and a second glance through the 19 paintings that preceded Eliza Grammont showsthat, even in the Gallery's first months, the trustees had kept an eye out for what might tickle the curiosity of the public. The first of the prime ministers they secured is NPG 4, a portrait of Spencer Perceval. This is not an obvious pick until the premiership's sensational and premature end is taken into account: Perceval had been dramatically shot dead in the lobby of the House of Commons by a deranged bankrupt.
The subject of NPG 7 is a more glamorous figure, Sir Walter Ralegh by an unnamed artist. His pearl-encrusted costume is spectacular and the fur-trimmed cloak trailing over his left shoulder must have had folklore-conscious Victorian visitors exclaiming, "Ah yes, that cloak!" NPG 13 is again a raffish, but more minor celebrity, John Horne Tooke, a renegade clergyman, MP and one-time friend of John Wilkes, Voltaire and Laurence Sterne.
So the NPG can be seen as operating from the start as a superior sort of rival to the waxwork shows, of which by far the most successful, Madame Tussaud's in Baker Street, had been attracting even upper-class society - including the old Duke of Wellington, a regular visitor to the Chamber of Horrors. The NPG trustees and their long-serving first secretary, George Scharf, knew the gallery would not get visitors by piously parading dull half-lengths of the great and good. They may never, like Tussaud's, have gone in for criminal horrors - there is a drawing of Jonathan Wild in the collection, but no Crippen or Hindley - but they have never minded giving wall space to sitters of seedy, even sinister notoriety.
One early example is NPG 418, Thomas Blood, in a 17th-century portrait attributed to Gerard Soest. The Anglo-Irish Blood was a murky character. Possibly an agent provocateur, he tried to foment rebellion in Ireland in the 1660s then, turning to grand larceny, attempted to steal the crown jewels. A more recent rogue is Leon Engers Kennedy's cultic portrait of the red-robed satanist Aleister Crowley, painted during the first world war looking every inch the evil genius. But the gallery has tended to shun political extremists. Glyn Warren Philpot's portrait in oils of Oswald Mosley was done before he was a fascist and is a tame affair. It shows an English gent in a soft weekend collar and tie, while historical curiosity demands an image from a decade later, with the jackboots and the shark-shiny black shirt.
The decision to collect portrait photographs alongside the paintings (beginning with one of Mrs Beeton in 1932) was the first of two momentous changes to the NPG's orientation during the 20th century that eventually widened the gallery's scope beyond that of the "primary collection". Photography gave the opportunity to enlarge the range of images vastly and at relatively small cost. As a result, and especially after the 1960s, the gallery began to expand beyond the historical portraiture of dignitaries and beyond "fine art": it became a receptacle for pictures of people in all walks of life, captured on cigarette cards, cartoons, news photographs, advertising images and even family snapshots.
The second change came in 1969 with the abandonment of the 10-years-dead rule for the primary collection. Together with the first commissions specifically for the gallery, this move allowed the NPG to take the shape it has today.
It is a two-headed beast, one gobbling up mass imagery in an age of instant celebrity, the other thinking about the nature and purpose of portraiture in art - and occasionally doing both at the same time. Beside the hundreds of historical portraits, exciting new work can always be seen there, and is enjoyable (or annoying, debatable, undigestible) on many levels.
Look in turn at three portraits of scientists now on display and you can see this multiplicity at work. Maggie Hambling's magisterial portrait of the chemist Dorothy Hodgkin in old age, at work at her desk on the structure of insulin, is a conventional painting that concerns the mystery of science, but also of representation itself. By giving Hodgkin four arms, and making her do two things at once, the artist injects the weirdness of Magritte into an otherwise natural-seeming composition. Tom Phillips' portrait of the synaptic pharmacologist Susan Greenfield also multiplies the pose or action - not by two but by 22,500. In this number of frames, 169 drawings of Lady Greenfield are presented on a computer screen, as well as photo-graphy and video, in a hypnotic, constantly changing combination of overlaps and merged imagery.
Then there is Marc Quinn's representation of the geneticist Sir John Sulston, labelled as "a sample of the sitter's DNA in agar jelly mounted in stainless steel". This object claims to be a true portrait because the DNA encodes the essence of Quinn's "sitter". Visually it approximates to a lay-person's idea of what a forensic sample might look like, namely several symmetrically arranged blobs of sago pudding. It is a joke, of course, a conceit targeting the most patently obvious quality of a portrait - that it provides a distinctive visual experience of the sitter. But for it to do so at the NPG itself is a tribute to the institution's present self-confidence.
It was on a different wave of self-confidence that Lords Stanhope, Ellesmere and the others floated the idea of a National Portrait Gallery 150 years ago. They wanted a gallery that would reflect the Whig view of history, a parade of personalities who could fairly be seen as the cultural and political ancestors of what had only recently become an administratively centralised world empire. What they got, and we have still got, is rather different: a gallery that shows art in the service of human individuality.
National Portrait Gallery, London, tel 020 7306 0055. The NPG's 150th anniversary partner is Herbert Smith
