A drug-driver from Ivybridge has been jailed for threatening his mother with a knife when she tried to get him to pull over.

Thomas Montgomery had taken so much valium that he started veering around the road and falling asleep at the wheel as he drove on country roads near Crediton.

His terrified mother Katherine tried to keep him awake and begged him to stop but he responded by pulling out a lock knife and said “I’m going to stab you”.

He pulled into a layby, opened the blade, and put it to her throat. She suffers from multiple sclerosis and struggled to get out of the car to escape him.

She was rescued by a passing motorist and the police were alerted. They found him unconscious in his car at Crediton station and had to smash the driver’s window before they could arrest him.

Montgomery, aged 23, of Erme Road, Ivybridge, admitted making threats with a bladed weapon, driving while disqualified, and failing to provide a specimen for analysis.

He was jailed for a year and seven months, and banned from driving for three years after his release, by Judge Timothy Rose at Exeter Crown Court.

He also made a restraining order banning further contact with his mother for five years.

He told him: “You threatened your mother with a knife and caused her a great deal of shock and distress. You effectively put it up against her throat but did not go as far as to harm her.”

Mr Nigel Wraith, prosecuting, said Montgomery was banned from driving but cajoled his mother into lending his car so he could drive his girlfriend from the mother’s home in Winkleigh to her home in Uffculme.

He began to drive erratically and dangerously on the return journey and his terrified mother had to nudge him to keep him awake.

Mr Wraith said: “His mother challenged him about his driving and he told her that if she carried on like that, he would smash her face in.

“He took some pills and said ‘you must want me to stab you’ before he pulled into a layby and said ‘you have provoked me, I’m going to stab you’.

“She was shocked and tried to escape from the car. He grabbed her by the arm and shouted for her to get back in but she punched him and managed to get out.”

She flagged down a motorist who gave her refuge in her car and the police later found Montgomery at Crediton station. He refused to give a blood test to check what drugs he had taken but a vial with five pills was recovered.

He later told police he had confronted his mother ‘because she would not shut up’. She wrote a victim statement saying she was extremely vulnerable because she suffers from multiple sclerosis.

She said she felt terrified and helpless and did not know what was going to happen during the incident.

Miss Bathsheba Cassel, defending, said Montgomery became addicted to alcohol and drugs after going into care at the age of 12. He is now motivated to address these issues and mental health problems of depression and anxiety.

He had taken 12 valium tablets on the day of the offence and wants to apologise to his mother for the distress he caused her.