A man who stabbed a pensioner in a Southampton street felt an urge to kill triggered by severe delusions brought on by a mental illness, a court heard.

Paul Humphries claimed he attacked John Willdig because he needed to “get answers” to fears that he was “under surveillance” and his food was “being drugged”.

Mr Willdig died after being fatally stabbed outside a house in Morris Road, The Polygon.

Humphries, 36, of Morris Road, denies murdering Mr Willdig, 70, on the grounds that he was mentally ill at the time and did not intend to kill the pensioner or was responsible for his death.

Giving evidence at Winchester Crown Court, Humphries told how he was diagnosed with paranoid schizophrenia in 2006 and had previously been sectioned.

He claimed suspicions that he was “under surveillance” and his food was “being drugged” began to grow in the months before the attack on June 23 of last year and told the court: “I felt that if I killed someone I would get answers to what was happening to me.

"It had been on my mind for a long time but got worse at the beginning of the year.”

He said the urge was intensified by everyday signs and slogans such as “just do it” he saw written on a T-shirt and that he interpreted a car number plate reading “KKK” as meaning “kill, kill, kill”.

But he refrained telling psychiatrists of these feelings for fear of being sectioned and “losing his freedom”, including at an appointment the day before the attack, the court heard.

On the night of the stabbing Humphries was in his bedroom when landlady Caroline Jarvis telephoned him from outside asking to help bring bags in from a taxi, jurors heard.

Humphries claimed he picked up the knife because he was feeling “unstable” and knew her ex boyfriend John Willdig was downstairs who he accused of previously trying to “provoke” him Humphries.

The court heard Humphries used the knife when Mr Willdig verbally abused and swung a punch at him.

He described his actions as “red mist” without any feeling or emotion, it was heard.

Mr Willdig died at Southampton General Hospital from five stab wounds, two to the neck, one severing an artery and three more to the back - one piercing his lung.

Proceeding.