A father who fitted a spy camera above his 21-year-old son’s bed to watch him have sex with a girlfriend has been jailed for four years.

The 53-year-old married man could hear noise coming from the couple’s bedroom and was “curious” about their sexual exploits, a court heard.

He installed the spy camera in the loft above their bed and then recorded the pair having sex - even linking the video feed to a television in the kitchen so that he could watch while cooking.

A judge was told how the father’s twisted campaign of voyeurism only came to an end when his younger daughter accidentally switched to a different channel on the TV and was confronted with live images of her brother’s bed.

The teenager then told the son’s girlfriend and between them they climbed into the attic and discovered the camera.

They later discovered a naked screenshot of the 19-year-old girlfriend, taken from a video of her having sex with his 21-year-old son.

The man, who cannot be named to protect the identity of his children, bowed his head in shame as a judge told him he would face jail for his “appalling” crimes against his own family.

It then emerged that he had sexually abused his 12-year-old daughter at their home in Faringdon, Oxon.

Judge Ian Pringle QC said: “It is an appalling abuse of trust.

“A greater breach of trust is difficult to imagine. You wanted to spy on their sexual activity, curious as to what was going on and you even printed out a picture of your son’s girlfriend naked.

“You say you don’t know why you committed these offences and that it gave you no real sexual gratification.”

The judge, sitting at Oxford Crown Court, was told that the middle-aged father had also conducted a campaign of sexual abuse against his 12-year-old daughter, touching her over and under her clothes.

After the hidden spy camera was discovered the youngster plucked up the courage to tell her mother, who called the NSPCC.

Defending the father, Jenny McVeigh said it was still unclear what had motivated him to commit such abuse.

“What he is unable to put into words at this stage is the motivation behind his behaviour.

“He didn’t feel an immediate feeling of sexual gratification from it.

“His concern was, remains and continues to be how his daughter is coping.”

The father admitted eight counts of sexual activity with a child and two of voyeurism and was sentenced on Friday.