A British man with a history of sleepwalking strangled his wife because he was convinced that she was an intruder who had broken into their camper van.

Brian Thomas, 59, and his wife Christine, 57, were on vacation in West Wales when he attacked her in the middle of the night.

Prosecutors accepted the findings of medical experts who said that he had a sleep disorder. They told Swansea Crown Court that they would not seek a conviction for murder or manslaughter.

The couple had been asleep in their camper when they were disturbed by “boy racers” and decided to move. After they went back to bed, Brian Thomas had a nightmare in which the youths broke into their camper van.

He woke up alongside his lifeless wife’s body and called for emergency assistance. In a tape of the call played to the jury he was heard telling the emergency operator: “I think I’ve killed my wife. Oh my God. I thought someone had broken in. I was fighting with those boys but it was Christine. I must have been dreaming or something. What have I done? What have I done? Can you send someone?”

Thomas was crying and shaking when he was found by police officers 10 minutes after making the call. He had said of his wife: “She is my world.”

Paul Thomas, for the prosecution, said: “The defendant accepts that he caused the death of his wife, but the prosecution (does) not seek a verdict of guilty to murder or manslaughter. Instead, very unusually, we seek what is called a special verdict, a verdict of not guilty by reason of insanity.”

The court was told that the Thomases were a “happy, devoted couple” who were due to celebrate their 40th wedding anniversary. Thomas, of Neath, South Wales, had suffered from sleep disorders for 50 years. Medical experts had carried out tests that confirmed his behavior was “consistent with the legal concept of automatism."

The prosecution said: “In other words, at the time of the killing the defendant was asleep and his mind had no control over what his body was doing.”

If he is found not guilty due to insanity he will be subject to a psychiatric hospital order and could be detained indefinitely.

Click here to read more on this story from the Times of London.