Royals, politicians, actresses - hacks have preyed on them since the 1700s, writes Stella Tillyard
Flash photographs, long lenses, fast bikes, satellite transmission - we think of press intrusion as something quintessentially modern. But although the technology may belong to the last 30 years, the phenomenon itself is over two centuries old. It was created by the simultaneous birth of the gutter press in the 1740s and the rise to stardom of actors and actresses on the London stage.

The singers, actresses, and actors of the mid-18th century were the nation's first pop-stars and national celebrities, and although they actually met their public no more often than their modern counterparts, the people, through prints, popular biographies, and stories in the press, felt that they knew and understood them. "The public very well knows that my life has not been a private one; that I have been employed in their service," wrote the wily old actor Colley Cibber in 1740. He was disingenuous, knowing that, far from being slaves of their fans, actors nurtured their stardom, feeding stories to growing numbers of periodicals and writing sensational autobiographies.

Encouraged by the success of this new gossip, reporters began to pay and be rewarded for scraps of scandal. By the 1750s they had turned their attentions to a new set of public players: the aristocracy. It was more risky to expose aristocrats than actors, but by then a new way of thinking about character and personality - "sensibility" as it was called - had swept through the reading public. Sensibility stressed the importance of feeling and domestic behaviour in the understanding of character. It appealed particularly to women and justified a new interest in the private lives of public figures, legitimising the fascination that readers already had for scandal and romance. Editors, then as now, and gesturing to this new theory, could piously claim that exposing the private activities of those in court or government was in the public interest, well aware that in fact romance and scandal sold newspapers.

Henceforth no aristocrats, particularly if they were also politicians, courtiers, gamblers, or womanisers, were safe. But while a man such as Earl Grosvenor, ridiculed as a cuckold in 1770 by a famous print showing his wife and her lover being spied on while making love, might lose face and esteem by press exposure, women could be ruined for ever.

Perhaps the first to endure the full force was Lady Sarah Lennox. In 1760 the young George III, who had just come to the throne and was himself the subject of great public interest, fell passionately in love with Lady Sarah, who was beautiful, witty and just 15. The romance was advertised with the publication of a print of the courting lovers and their identities signalled by the inclusion of a large royal oak and, in the background, Lady Sarah's London residence, Holland House. The King was forbidden to marry Lady Sarah, but the press continued to be interested in everything she did, and when, nine years later, she abandoned her husband for the arms of her lover Lord William Gordon, they were not far behind. The couple tried to elude reporters by assuming false names and keeping on the move but they were traced from Southampton to rural Scotland and surprised by a reporter from the successful scandal sheet the Town and Country Magazine, who posed as a traveller needing hospitality and duly supplied his readers with a long account of the lovers looks, happiness and circumstances. Lady Sarah was never able to go to court again.

After the French Revolution and during the long Napoleonic Wars, the temper of the nation changed. Sensibility, with its emphasis on feeling and domesticity, seemed unsuitable to a country enduring a long war. Out went emotion and in came the much more public and masculine virtues of loyalty, duty, and reserve. The long senility of George III made it difficult to report court scandal. Despite the respite of the Regency, which culminated in the sensational trial for adultery of Queen Caroline in 1820, the reclusiveness of the Victorian monarchy and the disappearance of women from public life confirmed the backlash.

The founding of the tabloid, or "yellow" press in the 1890s put gossip and romance back onto the printed page.But it was the publication of Lytton Strachey's Eminent Victorians in 1918 that finally blew the lid off Victorian respectability. Strachey used Freud to justify describing the tawdry vices and earliest traumas of public figures. Like sensibility, Freud's theory of the unconscious brought emotional experience to the fore. By insisting that the real exploration of character was to be found in early and intimate life, it allowed journalists, editors, and readers to declare open season on the famous .

But things had changed since the 1750s. As Strachey realised, and as newspaper and magazine sales have demonstrated ever since, the need to know about others' lives and emotions was much deeper than 150 years before. The British people had been transformed by Victorian morality. We have become more reserved, more repressed, and therefore prurient rather than simply curious. So the backlash against the press will now be short-lived. While Diana becomes a popular saint, it will be the unfortunate Princes who will become the focus of the public need for vicarious emotional expression. If Prince William has inherited both his father's seriousness and his mother's ability to manipulate the media, he may become a formidable and popular monarch.