A MAN who admitted killing a father-of-four in a street attack is nevertheless battling to have his manslaughter conviction overturned at London's Appeal Court.

Carl Mason, no fixed address, was alleged to have chased Michael Brolly through the streets of York in September 16, 2001, and then kicked and stamped him to death.

Mason, 23, later admitted manslaughter, but nowhis legal team argued he should have been allowed to vacate his "mistaken" guilty plea in June, 2002.

Mr Justice Treacy - who jailed Mason for four years - had declined his request to change his plea to not guilty, but that decision was attacked at the Court of Appeal as "wrong in law" by his counsel, Robert Smith, QC.

The barrister told three top judges that key prosecution witnesses had been undermined shortly after the guilty plea was entered.

If he had been aware of what would happen at the time, Mason - who was originally charged with murder - would never have opted to plead guilty, said the barrister.

He only did so on the "strong" advice of his legal team, argued Mr Smith, as they were concerned at what then appeared to be the strength of the witness evidence against him.

But James Goss, QC, for the Crown, argued that the strength of the case was only one of the reasons why Mason owned up.

The barrister said Mason's legal team were also concerned at the much longer sentence he would be likely to receive if convicted of the more serious murder charge after a trial.

But Lord Justice Potter, who was hearing the case with Mr Justice Hunt and Mr Justice Tugendhat, observed it was strongly arguable Mason should have been allowed to vacate his guilty plea.

"Whatever the reasons, he was faced with the situation where he knew on the facts the case against him was a very weak one," said the judge.

Mr Brolly was attacked after being chased through York city centre, and was found unconscious by police in Low Ousegate.

The killing of the 34-year-old, of Margaret Street, Walmgate, was sparked after an incident in a city centre bar.

After listening to a day of legal argument, the judges reserved their decision on Mason's appeal.

Updated: 10:37 Monday, November 01, 2004