Sinclair also maintains that the minimum term imposed on him as he was jailed for life for the brutal killings of 17-year-olds Helen Scott and Christine Eadie in October 1977 was excessive when compared to other cases of murder.
The victims were last seen by police on patrol outside the World’s End pub in Edinburgh’s High Street. Miss Eadie’s body was found the next day at Gosford Bay, Aberlady, in East Lothian. She was naked, gagged and had ligatures across her mouth and around her neck. Miss Scott was found dead, naked from the waist down, in a field near Haddington about five miles away. Her hands were tied behind her back. Tights and a belt had been used as a ligature round her neck.
Sinclair’s counsel Ian Duguid QC told judges at the Court of Criminal Appeal in Edinburgh that the 37-year tariff imposed on Sinclair, 70, by Lord Matthews was “somewhat symbolic” because it was 37 years between the offences and his conviction last year.
He said the chances of Sinclair being around to have his case for release considered by the parole board were “negligible”.
The convicted murderer and rapist was the first person to be prosecuted following new double jeopardy legislation after he was previously acquitted of the rape and murder of the teenagers at a trial at the High Court in Edinburgh in 2007 on a no case to answer submission.
He was charged with committing them with his brother-in-law Gordon Hamilton, who died in 1996.
Judges cleared the way for a fresh trial after ruling that it was highly likely that a reasonable jury would have convicted on new evidence over advances in DNA and evidence from the previous trial.
Lord Matthews told Sinclair: “You have displayed not one ounce of remorse for these terrible deeds.
“The evidence in this case, as well as your record, details of which have now been revealed, shows that you are a dangerous predator, who is capable to sinking to the depths of depravity.”
Sinclair was ordered to be detained in 1961 as a 16-year-old for the culpable homicide of an eight-year-old girl.
In 1982, Sinclair received a life sentence for rapes and indecency offences against girls.
He was given a further life sentence in 2001 for the 1978 murder of 17-year-old Mary Gallacher, who was sexually assaulted in Glasgow.
The Crown had included information on the life sentences previously imposed on Sinclair as documentary productions in the indictment for Sinclair’s trial over the World’s End murders.
Sinclair dropped attempts to appeal against his conviction previously.