As she stepped out of her home in Chelsea, West London, Prince William’s girlfriend was confronted by about twenty photographers and five television crews anxious to record her short walk to her car as she left for work as an assistant buyer for the fashion chain Jigsaw.

Despite an unofficial agreement with Clarence House that cameramen would stay on the other side of the street and shoot her from a distance, she was mobbed. Witnesses said that television crews broke ranks and the rest followed.

In photographers’ parlance it is an activity known as “hosing the Doris” — keeping the button pressed and taking as many frames as possible in the shortest conceivable time of any female celebrity.

At one stage Ms Middleton held up her hand to cover her face as a female freelance photographer moved within two feet of her. She has so far shown considerable patience with the media attention, but she was plainly irritated.

For Prince William, irritation has turned to open annoyance, and a desire to find legal ways of protecting his girlfriend from the kind of attention that blighted the life of his mother.

His aides said yesterday that he wanted “more than anything” for the paparazzi to stop hounding Ms Middleton. As reported in The Times yesterday, the Prince of Wales’s lawyers are examining a number of possible legal routes to stop what they regard as a serious nuisance, including criminal or civil proceedings for harassment, or even an approach to the European Court of Human Rights.

They are also in touch with the Press Complaints Commission, which claims to have had some success recently in making unofficial approaches to newspapers to lay off certain celebrities who do not welcome the attention.

Two years ago Princess Caroline of Monaco won a landmark judgment in Strasbourg when the court ruled that photographs of her published in a magazine without her consent were a breach of her privacy.

Chris Harris, a senior staff photographer for The Times, was despatched to Chelsea with instructions to photograph the media mob lying in wait for Ms Middleton.

He said: “She appeared in my shots, but at a distance. You can’t tell a picture story without the principal figure appearing somewhere in the image.”

News International, publishers of The Times, The Sunday Times, The Sun, the News Of The World and the freesheet thelondonpaper, made it clear yesterday that it would not use paparazzi picures of Ms Middleton in any of its titles. The announcement was welcomed by Clarence House.

Photographers working for recognised newspapers say that they photograph only what happens in front of them and that they do not intrude on privacy. Self-employed paparazzi, they claim, make their living by getting close to a celebrity and trying to provoke a reaction.

“A picture of Kate pointing at a camera and clearly saying ‘sod off’ is clearly worth more on world magazine markets than one of her walking sedately down a street,” Harris said.

Alan Williams, chief executive of Big Picture, one of the world’s leading agencies for selling paparazzi pictures, denied intrusion. “We took Kate’s picture yesterday because it’s a news picture,” he said.

“She’s in the news. If she wasn’t, she wouldn’t be in the least bit interesting.”

Fascination with Ms Middleton has dogged her since she left St Andrews University, where she and Prince William were students, sharing a cottage. It has moved into a far higher gear recently on the back of reports, so far unfounded beyond Ms Middleton’s presence at her boyfriend’s passing-out parade at Sandhurst last month, that the couple might soon announce their engagement.

Prince William has reported for duty with the Blues and Royals cavalry regiment, where he is known as Cornet Wales, at Combermere Barracks, Windsor. In March he begins five months of training at Bovington Camp in Dorset.

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