A man who bludgeoned a prison worker while serving a sentence at Norwich Prison can seek his freedom in less than three years, after a review of the case by a High Court Judge.

A man who bludgeoned a prison worker while serving a sentence at Norwich Prison can seek his freedom in less than three years, after a review of the case by a High Court Judge.

Darren Blanchflower was a 21-year-old convicted robber when, aggrieved at criticisms of his work, he murdered decorating instructor Walter Arnold in May 1990.

Blanchflower rained blow after blow on Mr Arnold with a hammer, killing him in a pre-planned attack after taking a major dislike to a man liked by both prisoners and staff.

He admitted the murder at Norwich Crown Court in February 1991 and was jailed for life by Judge Ian Kennedy.

Yesterday, ruling on the minimum term - or tariff - which Blanchflower must serve before being allowed to apply for his release, High Court Judge Mr Justice David Clarke said he would serve no less than 20 years.

That means he will be able to apply for release as early as May 23, 2010, although he will still have to convince the Parole Board he no longer poses a danger to the public.

Psychiatric reports put before the Norwich judge in 1991 said Blanchflower struggled with a “psychopathic personality and an abnormality of mind”.

He later volunteered to be treated by a top psychotherapist in an attempt to cure his tendency to violence and featured in a BBC Panorama documentary - entitled Predators - on the subject in 1997.

In written arguments put to Mr Justice Clarke at the Royal Courts of Justice, lawyers representing Blanchflower suggested that his case justified a tariff of just 12 years, allowing him to apply for parole immediately.

Blanchflower, now 38, was a very young at the time of the killing and had put his hands up to the murder immediately and made excellent progress in the years already spent behind bars, it was argued.

But, giving his ruling, the judge said Blanchflower was lucky to receive the term he did. “If he were to be sentenced today, I would expect a minimum term of some 25 years to be set, this being substantially longer than the 20-year term by which I am limited in this review,” he said.

“There is, and in my view always was, a powerful public interest in the imposition of very severe sentences for the murder of police or prison officers acting in the course of their duty.”