The girlfriend of a 'rookie' policeman told how she screamed for help as her boyfriend lay in a pool of blood after being slashed in the face with a stanley knife.
Newly qualified PC Shuaib Gafur, 25, needed 30 stitches to his face after he confronted a dangerous driver at a petrol station.
The off-duty PC told Isleworth Crown Court he picked up his girlfriend Nehar Aggarwal from work and they were driving back home to west London when they were 'cut up' twice by the driver of a blue van.
Sitting behind a screen, Mr Gafur said: "I saw this blue van being driven erratically. He was driving from one lane to another and swerving between cars and other vehicles."
After driving along the A4 towards Osterley, the blue van stopped at the Tesco petrol station and Mr Gafur followed.
He asked the defendant, Faisal Mohammad, of Osbourne Road, Acton, what was 'up with his driving' before being knifed in the face from his nose to his jaw.
The officer was taken to West Middlesex University hospital where he needed more than 30 stitches inside and outside his facial wound and was treated to wounds on his shoulder and back.
Mohammad, 30, denied wounding PC Gafur, causing him grievous bodily harm on March 25 and claimed he acted in self-defence.
But the married father-of-one was sentenced to five years on Tuesday. The judge, Recorder James Mulholland told him: "This is an extremely serious matter and I have little choice but a substantial custodial sentence.
"You were seen sitting in your van waiting and preparing for this man's arrival with a stanley knife in your hand and you lashed out at him several times with it.
"His wounds included a facial injury which needed some 30 stitches and I have no choice but to conclude that you have shown little if any remorse for your actions."
Mohammad's wife and the mother of his child fled the court in tears as he was taken to away.