Barbara Mayo was discovered in Ault Hucknall Wood, Derbyshire, a mile and a half from junction 29 of the motorway, on 18 October 1970. The 24-year-old student teacher's killer has never been traced, although the investigation into her death was never officially closed.
When it was launched it was the biggest probe ever undertaken by a British force, with 120 officers involved at its height.
The Derbyshire force has now reopened an incident room at Chesterfield police station following what it described as a "major new development".
Police last night refused to disclose the nature of the fresh information, but will announce it on Monday along with a hotline number for the public to call.
Assistant Chief Constable Don Dovaston said: "This investigation has never closed since Barbara's body was found in Derbyshire in the autumn of 1970.
"We will be releasing important new information which may help us bring the killer to justice."
Police are expected to renew their appeal for sightings of Barbara, who was last seen carrying a bag with a distinctive elephant motif.
She had apparently set off from her home in London at around 11am on October 12 to hitchhike to Catterick. Police believe she was killed that day.
More than 47,000 statements were taken during the first four years of the inquiry into her death.
Police interviewed 126,300 people, checked more than 72,000 Morris Traveller vans and took 78,000 calls in their incident room.
But, despite checking the records of 28,000 criminals and following up more than 76,000 leads, they never found Barbara's killer.
Seven years ago officers established similarities between her murder and that of Jacki Ansell-Lamb, who was killed in Cheshire in March of the same year.Reuse content