PC Geoffrey Fox, Det Con David Wombwell and Sgt Christopher Head

Harry Roberts has served 37 years of a life sentence for murdering PC Geoffrey Fox, 41, Sgt Christopher Head, 30, and Det Con David Wombwell, 25.

Roberts claims his human rights are being breached by the Parole Board, which has been assessing whether he should be released.

The board has ruled that Roberts' lawyer should not see some of the reports which have been made into his suitability for release.

Instead, a special advocate would be appointed by the board to deal with the evidence, and could have no contact with Roberts or his legal team once the files were seen.

Simon Creighton, Roberts' solicitor claims this is only normally done in cases involving foreigners to protect national security.

Roberts has served 37 years of a life sentence

The reports about Roberts that have been disclosed are "very positive" according to his solicitor.

Mr Creighton said Roberts was being made a "special case" and normal procedures for dealing with other prisoners have not been followed.

He claims this means Roberts is unable to defend himself against unknown allegations.

"He is struggling to get a fair procedure," Mr Creighton said.

"You can't have a fair decision about whether someone is to be released if you're not telling them what information you are going to consider as part of your decision. It flies in the face of natural justice.

"I think it infringes his human rights."

Kray widow

Roberts was allowed to go to an open prison in 1999 but returned to a closed one after making unauthorised journeys - including meeting Kate Kray, the widow of East End gangster Ronnie Kray.

Roberts is now in Channings Wood prison near Newton Abbot, Devon.

The murder of the three plain-clothes officers was one of the most high-profile crimes of the 1960s.

The officers were gunned down in front of children playing in a street in Shepherd's Bush, west London after they pulled over a van containing Roberts, John Duddy and John Witney, following an armed robbery.

Roberts shot dead Det Con Wombwell at point blank range and then turned the gun on Sergeant Chris Head, shooting him in the back. Duddy then shot dead PC Geoffrey Fox.

The judge at the men's trial, Mr Justice Glynnes, told the gang in December 1966: "I think it likely that no Home Secretary, given the enormity of your crimes, will ever think fit to show mercy by releasing you."

Duddy died in prison in 1981 aged 51 and getaway driver Witney, 69, freed in 1991 died at his home in Bristol in 1999.