Northamptonshire Police said on Friday they now think Valerie Haycock, who was 19-years-old when she went missing from Northampton in 1967, may be living in Ireland.
Police said of the seven new sightings of Miss Haycock, six were in southern Ireland.
She was last seen by her family boarding a bus from Northampton to Newport Pagnell and then to Luton in Bedfordshire.
Two Irishmen
Before she disappeared she told her family she had got a job as a nanny for a family living on a farm in the Luton area.
Until then she lived with her parents in Forest Road in Piddington, Northamptonshire.
Police had always suspected she may have run off with two Irishmen who were contracted by the local council to paint white lines on freshly resurfaced roads.
Earlier this year a new witness told police he saw Haycock with two men in the Britannia public house on Barrack Road in Northampton, about a week after she was reported missing.
Valerie, who would now be almost 55, is being urged to contact her family or the police.
The Southern Ireland desk of Interpol is now carrying out inquiries and following up the latest leads.
~RS~a~RS~International~RS~q~RS~~RS~z~RS~18~RS~)