The complainant, who was 15 at the time, had told the court that a Jason Donovan tape was playing in PC Anthony Hill's car on the day of the alleged rape, in February 1988. But PC Hill, 47, produced the cassette, and another by the all-girl pop group Bananarama, to prove that they were recorded in 1989, so the offences could not have taken place on the date the girl alleged.
The jury had asked to see the two cassettes while it considered its verdicts. It found PC Hill, of March, Cambridgeshire, not guilty of rape and an alternative charge of indecent assault.
He admitted having sex with the school prefect at Thetford Forest in Norfolk, after meeting her at a careers convention. But he claimed throughout the trial that the girl, a virgin, had consented to sex and he thought she was aged 16 or 17.
After the verdict, PC Hill refused to comment but a spokesman for the Cambridgeshire Police said his career as a community affairs officer was still 'in the balance'.