A moped rider pulled lumps of hair from a female constable’s head after she stopped him on Great Western Way.

And a hero bus driver came to the aid of officers after the 20-year-old they had stopped at around 8.45pm on Monday started to become aggressive.

Police said a local man had been arrested on suspicion of assault, theft of a motor vehicle and failing to provide a specimen for analysis.

Insp Rachel Hardy said: “This was a nasty incident – when officers attempted to arrest the man he was aggressive and continued to hit out at them, pulling chunks of hair from the head of a female officer leaving her in considerable pain.

"This kind of violence towards our officers who are simply trying to do their job will not be tolerated.

“We understand a bus driver pulled up at the side of the road while officers were detaining the man and assisted them in doing so – we are extremely grateful to him for his selfless actions.”

Wiltshire Police said officers had tried to arrest the moped rider on Great Western Way last night.

The man became aggressive, lashing out at the officers, and later refused to provide a specimen of breath at the roadside.