Yvonne Sleightholme's battle to prove she was wrongly convicted of a notorious Ryedale murder enters a crucial phase at the High Court on Friday.

Sleightholme was jailed for life in 1991 for the cold-blooded killing of Jayne Smith, the wife of her former fianc, in a remote farmyard near Salton, Malton, in 1988.

But she has always protested her innocence and two campaigners, David Hamilton and Margaret Leonard, have been seeking to take her case back to the Court of Appeal.

Last year, the Criminal Cases Review Commission turned down their application for the matter to be referred back.

Now the campaigners are going to the High Court in London on Friday to seek permission to move for a judicial review of the commission's decision.

Sleightholme herself, who has been hysterically blind since her arrest for the murder, is likely to be taken from jail to attend the hearing.

It was reported last May how the pair claimed to have unearthed fresh evidence about the case. They said the jury was never informed about all the large bootprints found in the farmyard by police - evidence which they said would have supported her case that hitmen had been involved in the murder.

They also said the jury was not told about a gap in a fence which could have been used by the killers to get away in a four-wheel drive vehicle.

The commission said then that it could only refer a conviction to the appeal court if, in its opinion, there was a real possibility it would not be upheld. "In this case, the commission does not feel there is such a real possibility."

The campaigners will argue that the commission failed to take proper account of some of their evidence - for example that photographs of the bootprints taken by the police were not disclosed to the defence.

However, they say the main thrust of their case will be that, while the commission accepted as fact that the jury did not hear about all the bootprints and about the gap in the fence, it refused to refer the case to the appeal court on the grounds that these and other matters should have been raised by defence lawyers at the original trial.

"Our argument is that it's not Yvonne's fault that these issues were not raised, because she had no knowledge of them at the time. She is now being punished for something over which she had no control," said Margaret.

"The new evidence which has been accepted as factually correct by the commission means there is now a different case to that which was presented to the jury, and it goes against natural justice if this case is prevented from reaching the court of appeal."

A commission spokesman said it would be contesting the application. He said: "It's up to the court to decide."

He added that the commission had so far been taken to judicial review on 13 occasions, and in every case its decision had been upheld.

Updated: 10:20 Wednesday, January 10, 2001