A father and son who meted out a fatal punishment beating to a North-East man have failed in a bid to overturn their murder convictions.

London's Appeal Court ruled circumstantial evidence alone had been enough for the jury to convict John Mawhinney, 51, and his 25-year-old son, Keith, of Tony Clark's brutal murder.

Lord Justice Auld accepted Crown claims that, "in the real world", the Mawhinneys were the "only candidates" for the killing. They had also concocted alibis and lied to the police, he said.

Mawhinney senior, a Northern Irishman with reputed links to the Ulster Volunteer Force, was jailed for life at Teesside Crown Court in December 1999 alongside his son after both were convicted of murdering Mr Clark in his home in Milton Road, Hartlepool.

A third man, Michael Casey - said to have lured Mr Clark's wife Shirley out of the flat so that the "punishment beating" could commence - was convicted of conspiracy to cause grievous bodily harm and jailed for four years.

The Crown claimed father and son, who was 19 at the time of the killing, caused fatal injuries after subjecting their victim to a savage beating with pickaxe handles.

The attack was said to have been retribution for a burglary of Mawhinney senior's flat in which a ring of "considerable sentimental value" was stolen.

Mr Clark never regained consciousness and died the following day.

Lawyers for the father and son argued their murder convictions were "unsafe" as they were based on the "deeply flawed" testimony of police informant, Zeiff Payne, who claimed during the trial that both men admitted to him their roles in the killing.

Mr Payne had told the jury the Mawhinneys confessed to him after the killing that "Mr Clark was like a jellyfish when they left him" and that they had "broken every bone in his body".

Edward Fitzgerald QC, for Mawhinney junior, described Mr Payne's evidence as "inherently unreliable", and claimed the witness was mentally unstable, a past cocaine dealer, and a proven liar.

But Lord Justice Auld, sitting yesterday (FRI) with Mr Justice Henriques and Mr Justice Beatson rejected claims that the trial judge should have directed the jury to ignore Mr Payne's testimony.

The judge, he added, had given the jurors at Teesside Crown Court a stern warning to treat Mr Payne's evidence with caution.