JK Rowling has won a High Court appeal in her fight to protect the privacy of her son from long-lens photography.

The court of appeal reversed an earlier judgment against the Harry Potter author, giving Ms Rowling and her husband the right to go to trial to prove that her five-year-old son's right to privacy had been infringed.

The case could result in a landmark ruling which would protect celebrities and their families from intrusion by photographers, even if they are pictured in a public space.

Ms Rowling and husband, Dr Neil Murray, claim that photo agency Big Pictures breached their son David's right to privacy and family life under the European Convention on Human Rights.

The photo agency took long lens photographs of David in November 2004 when the 18-month-old was being pushed in a buggy by Dr Murray in an Edinburgh street. The photo appeared in the Sunday Express magazine, which later reached a settlement with Ms Rowling.

In a key finding, the Master of the Rolls, Sir Anthony Clarke, said: “If a child of parents who are not in the public eye could reasonably expect not to have photographs of him published in the media, so too should the child of a famous parent.”

"In our opinion, it is at least arguable that a child of 'ordinary' parents could reasonably expect that the press would not target him and publish photographs of him."

The appeal judges ordered that there should be a trial to decide the matter unless a settlement with Big Pictures could be reached.

In a statement, the parents said: “We embarked on this lawsuit not because we were seeking special privileges for our children but because we wanted them to grow up, like their friends, free from unwarranted intrusion into their privacy.

“We understand and accept that with the success of Harry Potter there will be a measure of legitimate media and public interest in Jo’s professional activities and appearances. However, we have striven to give our children a normal family life outside the media spotlight.”

They said the ruling would give their children protection from “covert, unauthorised photography” and make an “immediate and material difference to their lives”.

Their solicitor, Keith Schilling, said: “This case is a major development in the law of privacy in this country.”

He said the ruling established a law of privacy for children from “intrusive photography”.

“It will have a profound effect, especially on certain sections of the paparazzi, but I am sure that the overwhelming majority of the media will welcome it.”

The appeal judges set aside a High Court ruling last year which struck out the claim against Big Pictures Ltd, which took the photograph, and ordered that there should be a trial of the issues unless they can be settled.

Big Pictures will have to pay the majority of the costs of the case, estimated at a total of £600,000.

Previously, the High Court judge Mr Justice Patten had ruled that it was artificial for the parents to bring the action in the name of the child. But Sir Anthony said : “The child has his own right to respect for his privacy distinct from that of his parents.”

In April, Ms Rowling appeared in a New York courtroom to oppose the planned release of a 400-page Harry Potter Lexicon, an A-Z guide derived from a fan website. She said that the book would interfere with her plan to publish her own Harry Potter encyclopaedia and donate the proceeds to charity, as she has already done with two smaller guides.

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