Gordon Aspden KC prosecuting said: “There was abundant evidence of long-term and persistent use of illegal drugs, which would have a significant impact on his mental health.

“The accused was aware of the effects that these drugs could have on his behavior having previously been hospitalized.

“However, he chose to use those drugs before his mother’s murder. He made decisions in this case.”

Mrs Bauld suffered four separate stab wounds on the morning of the attack and a pathologist determined the cause of her death was a back injury, the court heard.

Sentencing the defendant, Judge Timothy Spencer KC said: “This murder was terrible beyond imagination. It was a brutal and shocking way to take a life.

“Your mother died on the road in front of your house, and her house, with your father at her side, while life expired before you watching.

“The prosecution rightly describes the impact of his mother’s murder as incalculable.

“He must have been aware that his drug abuse was a factor in his mental health difficulties, but he continued to use drugs.”