A SOCIAL worker who blackmailed a colleague after he filmed them having sex at work was jailed for two years yesterday.

Married Desmond Ross, 43, threatened to send the video tape to the woman's boss when she tried to end their affair.

It showed the pair having sex twice - stopping in between to heat up a curry in the office microwave, a court was told.

Ross, 6ft 3in, hid a camera in an adjoining loo in the social services building but had to keep opening the door with his foot as it kept swinging shut.

The woman, who cannot be named for legal reasons, only discovered he had the video when she tried to end their affair in February.

She told police how he demanded they continued to have sex or he would send the tape to her Durham County Council boss.

Ross, of Grasmere Grove, Crook, County Durham, pleaded guilty to blackmail between February 1 and March 25.

He was cautioned by police in September 2000 for harassing another female colleague, with whom he had an affair from February 2000, Teesside Crown Court was told.

Jim Withyman, defending, said that Ross, married with two grown-up children, had been prepared to leave his family and marry his blackmail victim.

"The demand was for the continuation of the relationship and hopefully to an engagement, but it is particularly ridiculous to think that any woman would agree to this," he said.

The woman initially alleged that Ross, who has since quit his job, demanded £750 and then £1,000 for the tape, said David Lamb, prosecuting.

Judge David Bryant told Ross: "Blackmail is a serious offence and is always an offence which is regarded by society as utterly contemptible.

"This was a planned offence; clearly you set the stage where you and your victim would perform in front of a camera, which you had placed there for the purpose.

"You then used the video taken by that camera to threaten the victim with effectively the loss of her job.

"I take the view that this is an offence which clearly requires a prison sentence, so serious that no alternative sentence could be appropriate and I see no exceptional features which would justify my suspending that sentence."