A Pembroke youth who beat a man to death after hitting him with a carrier bag full of lager cans has had his sentence cut after a judge rewarded him for his “exceptional progress” behind bars.

Mr Justice King described Dayna Carter as a very different person from the 17-year-old who beat and kicked 25-year-old Dean Evans to death in Pembroke in August 2006.

The judge added that having built up an array of academic and other qualifications in custody, 22-year-old Carter is genuinely remorseful and has even expressed his willingness to “start a dialogue” with his victim’s family.

Carter and his older brother Lee Carter were convicted of Mr Evans’ murder at Swansea Crown Court in February 2007 and each given life in prison.

Dayna Carter was ordered to serve at least eight years behind bars for his crime. However on Friday, in a very rare move, Mr Justice King told London’s High Court his conduct in custody was so “exceptional and unforeseen”

as to merit a nine-month cut in that term.

The judge said the attack on Mr Evans was triggered by “some trifling abuse” directed at Carter who responded by felling his victim by swinging a bag full of lager cans at his head, both brothers then kicking and stamping on him causing a fatal brain haemorrhage.

The Swansea judge who jailed Carter described the attack on Mr Evans as “appalling and unjustified.”

Mr Justice King said Carter’s youth had been a troubled one and prior to the murder he was drinking about eight cans of lager a day without which “he did not feel normal”.

Since being put behind bars, Carter had become captain of the prison rugby team, had completed a number of courses including an A Level in business studies and was one of only ten “red band” prisoners at the jail where he is being held.

The ruling means Carter can apply for release on parole in late 2013. He will then be freed if he can convince the Parole Board he poses no serious danger to society, although he will be subject to a prison recall is he puts a foot wrong ever again.