Harry Potter author J.K. Rowling has won her battle to ban further publication of a long-lens photograph of her son, in a privacy case her legal team called a major development in British law.

The initial claim by Rowling and her husband was thrown out by a London court last year, prompting the couple to appeal.

In a written judgment yesterday, a panel of judges upheld the appeal, a ruling which Rowling and husband Neil Murray welcomed.

"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 (Rowling's) professional activities and appearances," the couple said in a statement.

"However, we have striven to give our children a normal family life outside the media spotlight.

"We are immensely grateful to the court for giving our children protection from covert, unauthorized photography; this ruling will make an immediate and material difference to their lives."

Anthony Clarke, one of the judges hearing the appeal, said the child of a famous parent should have the same rights as that of "ordinary" parents.

"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," he said in the judgment.

The disputed photographs were taken on November 8, 2004 in Edinburgh while David, then aged under two, was being pushed in a buggy by his parents.

They were published in a Sunday Express magazine, prompting Rowling, 42, and her husband to sue Express Newspapers and photo agency Big Pictures and seek to block further publication.

The Express settled the claim, but last August High Court judge Nicholas Patten threw out the case against the agency.

Keith Schilling of Schillings law firm representing Rowling's family predicted the latest ruling could have a "profound effect ... on certain sections of the paparazzi.

"This case establishes a law of privacy for children in those cases where, understandably, the parents wish to protect their children from intrusive photography by the paparazzi," he said.

"I am sure that the overwhelming majority of the media will welcome it."

When asked for his reaction to the ruling, a spokesman for Big Pictures said: "No comment."

Big Pictures will have to pay the bulk of the costs of the case, expected to be hundreds of thousands of pounds (dollars).