A double murderer serving a life sentence has won a High Court victory in his long campaign for cosmetic surgery to remove a birth mark.

The publicly funded legal challenge by Dennis Harland Roberts, 59, could also lead to other prison inmates being considered for treatments they might otherwise have been denied because of an undisclosed policy operated by Justice Secretary Jack Straw.

The policy restricts prisoners' appointments for cosmetic and certain other treatments regarded as non-urgent - even though the Government publicly said prisoners were entitled to the same NHS treatment as the rest of the population.

Roberts won a declaration at London's High Court that Justice Secretary Jack Straw acted unlawfully and "contrary to good administration" in failing to disclose his full policy on medical appointments.

Coincidentally, Category A prisoner Roberts was represented in court by barrister Adam Straw - the Justice Secretary's nephew.

The court case led to the full policy being publicly revealed for the first time last week.

Following its disclosure, the Ministry of Justice agreed to reconsider Roberts' application to be escorted to hospital for laser treatment, if he could show the birth mark was having a negative impact on his health.

Nonetheless, Roberts and his lawyers continued the fight for a formal High Court declaration to make the legal position clear for other prisoners.

Roberts said the large, congenital port wine stain on the left side of his face, neck and shoulder had led to him being bullied at school and was linked to a violent temper.

He had previously received hospital treatment to remove it on three occasions, the last in July 2007. But appointments in 2008 were cancelled.

Roberts, who lived in a caravan near Newhaven, Sussex, was convicted at Lewes Crown Court in March 1991 of murdering an elderly couple.

Mr and Mrs Hadler, both in their 70s, were the victims of multiple stabbing after Roberts broke into their home in summer 1989.

He is currently at Durham's Frankland Prison and must serve at least 17 years of his life sentence before he becomes eligible for parole.

A consultant dermatologist recommended him for treatment for the birth mark in 2006.

The consultant stated: "This has always been an embarrassment to him, but he is now developing small vascular nodules within it and I think that laser treatment on the NHS is entirely justified."

Roberts said in a written statement to the court the treatment he had already received up to July 2007 appeared to have had some success, lightening and removing some 30% of the birthmark.

He said he was "extremely pleased" and was expecting an estimated further four sessions of treatment, but delays caused by the failure to provide him with hospital escorts had sent him into depression.

Mr Straw told the court that, as a result of being bullied at school, "he has a low tolerance for people commenting on his face. He feels self-conscious and fearful of his own reaction when he becomes aware of others looking at the mark.

"When the treatment was halted in July 2007, Roberts slid into depression and his violent temper re-emerged."

Mr Straw told the High Court the Government's full policy that had now come to light only allowed inmates "elective treatment" if there was "a negative impact on the prisoner's mental or physical health".

An elective procedure is one chosen by a patient or physician that, like cosmetic surgery, is advantageous but not urgent.

Mr Straw said the policy required need for treatment to be balanced against "public acceptability" issues, and the fact that category A escorts were "resource intensive, both for staffing and expenditure".

The new, undisclosed policy differed from the much broader policy currently published by the Justice Secretary, and relied on by the Government in a High Court case last year.

The broader policy gave inmates "access to the same range and quality of services as the general public receives from the NHS".

Mr Straw said: "There are clearly many healthcare services that would be provided on the NHS, even if it is not shown that there will be a negative impact on the inmate's health if the service is not provided."

These included check-ups, removal of blemishes, such as warts, prosthetics, fertility treatment and the removal of benign cancers.

Had Roberts known about the unpublished policy he would have sought a medical report to show the negative impact the birthmark was having on his health, and legal proceedings would have been avoided, said Mr Straw.

Mr Straw said it had been necessary to seek a High Court declaration "to prevent prejudice to many other prisoners with similar claims.

"Prisoners seeking medical treatment are entitled to know the correct policy so that they have a proper and fair opportunity to put forward their cases."

Agreeing with Mr Straw, deputy High Court judge Michael Suppertone QC declared in a judgment revealed for the first time today: "In my judgment it is contrary to good administration, and unlawful, for the defendant's full policy on medical appointments not to be published."