Campaigners who want to see Hanratty's conviction quashed said last night that they had prepared a 300-page dossier re-examining the evidence of the case and would be presenting it to the Home Office very soon.
Bob Woffinden, who produced a television documentary about the case in 1992, said last night it was important the matter was explored 'thoroughly and systematically' and that more than 'just one interview' would be required.
Hanratty was convicted at Bedford Crown Court in 1962 of killing Michael Gregsten, at Deadman's Hill on the A6 near Bedford.
It is understood that police last month questioned a man in north-west London who had previously confessed to the crime, then withdrawn his confession. The investigation is said to have started after the man sent a greeting card to Janet Gregsten, the murder victim's widow, last year.