Michael Finucane, eldest son of slain Belfast solicitor Patrick, said last week that he believes there will be a full public inquiry into his father's murder if Labour wins the next election: he expected party leader Ed Miliband to "keep his word". The record suggests that Mr Finucane may be in for a sad disillusionment.
Labour's record on collusion and cover-up in the north differs not at all from the Tories'. The most striking example is to be found in the response in 1978 of Secretary of State Roy Mason to revelations of RUC Special Branch brutality towards IRA suspects at Castlereagh Holding Centre - the venue where members of the same force are said later to have encouraged loyalist paramilitaries to murder a number of solicitors, including Pat Finucane.
Government papers released in 2008 suggest that Mason knew well what was happening in Castlereagh. But, pressed to set up a public inquiry, he opted instead for a review of detention procedures by crown court judge Harry Bennett.
There is an obvious parallel with Cameron rejecting calls for a public inquiry into the Finucane murder and, instead, inviting Sir Desmond de Silva QC to review evidence unearthed in previous investigations.
In the Commons on March 16, 1979, Mason declared that Judge Bennett had not found evidence to substantiate claims of inhuman treatment of detainees, but had discovered evidence of prisoners brutalising themselves in order to discredit Special Branch.
But Bennett's report hadn't given the Castlereagh interrogators quite as clean a bill of health as the Commons was led to believe. Mason had tossed in an extra fistful of whitewash.
Twelve days after Mason's Commons performance, Gerry Fitt, in protest, withdrew his support from the Callaghan government in a confidence vote. Labour lost by 311 to 310. The Thatcher landslide followed.
Even if Miliband in office creates a surprise and proves true to his word, the scope of any inquiry he sets up will be drastically restricted by the Inquiries Act, introduced by Tony Blair in 2005.
The Act gives the relevant Cabinet member - in the Finucane case, the Northern Ireland Secretary - power to dictate the inquiry's terms of reference and to determine which witnesses will be called.
The effect was first seen in the Inquiry into the INLA killing of Billy Wright at the Maze prison in December 1997.
The Wright Inquiry was one of six - the Finucane case was another - recommended by Canadian judge Peter Cory, who had been asked in 2002 to examine a series of collusion allegations.
Cory declared that, "The definition of collusion must be reasonably broad ... That is to say that Army and police forces must not act collusively by ignoring, or turning a blind eye to the wrongful acts of their servants or agents, or supplying information to assist them in their wrongful acts, or encouraging them to commit wrongful acts.
"Any lesser definition would have the effect of condoning or even encouraging state involvement in crimes, thereby shattering all public confidence in these important agencies."
Labour Secretary of State Paul Murphy intervened, using his powers under Blair's Act to impose a lesser definition.
The inquiry was to understand "collusion" to refer to a deliberate agreement to carry out unlawful acts: but taking deliberate decisions or turning a blind eye to a situation which facilitated unlawful acts would not amount to collusion.
Lord Saville commented that had the Blair Act been in force at the time he had been asked to chair the Bloody Sunday Inquiry, he would have refused the appointment. Heading an inquiry under these terms, he added, would be contrary to the judges' oath.
Judge Cory intervened from Canada: "The minister, the actions of whose ministry was to be reviewed by the public inquiry, would have the authority to thwart the efforts of the inquiry at every step. It really creates an intolerable Alice in Wonderland situation." Pat Finucane's widow, Geraldine, wrote to every senior judge in Britain, urging them not to sit on any inquiry into her husband's killing established under the 2005 Act: "I write to request that, if approached to serve on an Inquiries Act inquiry into my husband's murder, you, like Lord Saville and Judge Cory, refuse to accept such an appointment."
If the Finucane family has now been persuaded that Miliband in office would institute an inquiry outside the terms of the 2005 Act, it is fervently to be hoped that they are right. But Miliband has said nothing in public to sustain any such hope.
In the matter of the Finucane murder, there is an irresolvable contradiction between the interests of the state and the interests of justice. The chances of a Westminster government of any colour choosing justice are slim.