police officer James Cowan got his kicks by making sordid calls to schoolgirls - including one from his desk at the station.

The former Army regimental sergeant major made 590 calls, most of them to phone boxes outside schools, a court heard.

When he was arrested by colleagues, Cowan asked his son-in-law to claim responsibility, persuading him to make a signed confession.

But the 46-year-old PC's lies caught up with him and he was locked up for three months after admitting a charge of perverting the course of justice.

Newcastle Crown Court was told that Cowan made use of the fact that his rural police station in Broomhill, Northumberland, was quiet enough to make one of the calls.

However Cowan, of Ashington, Northumberland, was never charged with any sexual offences relating to the calls.

The court was told that police responded to a complaint from the headteacher of Newbiggin Middle School, Northumberland, and traced the call to Cowan in November, 1998.

But he talked his son-in-law David Maddock, 32, into admitting that he had made the call.

Suspicious detectives continued to monitor Cowan, convinced he was their man. They combed through two years of phone bills and checked his shift patterns in an attempt to prove he had been lying.

Cowan chose call boxes near schools in the hope that young girls and women would answer, so he could talk dirty to them and ask sordid questions.

Jailing him on Wednesday, Judge Gerard Harkins said: "You were a serving police officer. That is an aggravating feature in this case and the matter is so serious, a non-custodial sentence cannot be justified."

David Maddock, of Newbiggin, Northumberland, was ordered to carry out 200 hours' community service, after admitting perverting the course of justice