Key Points:

The lawyer for convicted double murderer John Barlow is flying to London today to appear before the Privy Council in a final attempt to clear his client's name.

Barlow was convicted and jailed for 14 years for the deaths of father and son businessmen Gene and Eugene Thomas, who were found shot in Wellington in 1994, 15 years ago to the day yesterday.

Lawyer Greg King said he was flying to London this evening for the Privy Council hearing on February 25 and 26.

The Privy Council would first decide whether it would hear the case despite the Court of Appeal in New Zealand refusing to do so, Mr King told NZPA this morning.

If it decided to hear the case, Mr King would put forward submissions relating to the FBI evidence used in the third trial which convicted Barlow after two hung juries.

The evidence compared bullets that killed the men to bullets Barlow had.

Mr King said he would argue that evidence had now been discredited and should not have been put before the jury.

"[It] misled the jury on a material issue."

Mr King said if the Privy Council decided to hear the case it had four options:

* refer the case back to the Court of Appeal in New Zealand;

* quash the convictions and leave the New Zealand courts to decide whether to try the case again;

* quash the convictions and acquit Barlow, which would mean the matter would be at an end;

* or reject the appeal.

If the council ordered the Court of Appeal to hear the case that would be a "significant step forward" as he had spent three years trying to get that to happen, Mr King said.

"But obviously we would prefer it if they simply quashed the convictions."