A THUG who stabbed a man in the back as he boarded a packed bus in a brutal revenge attack has been caged for four years.

Kenneth Kerr, 39, attacked John Gallagher, also 39, in May this year, stabbing him numerous times.

He pleaded guilty at Paisley Sheriff Court on Monday – the day his trial was due to start – after striking a deal with prosecutors.

Kerr admitted leaving Mr Gallagher badly hurt and scarred by the assault, in exchange for prosecutors deleting claims the knife attack also left him permanently impaired, scarred for life and placed his life in danger.

Procurator fiscal depute Alan Parfery said the attack took place at around 11.15am on May 20 this year, as Mr Gallagher was boarding a McGill’s bus in Neilston Road, Paisley.

Kerr had lain in wait for his victim, hiding in a doorway near the bus stop.

Mr Gallagher was taken to hospital, where he received three stitches to close the stab wound on his back and two stitches to close a wound on his shoulder blade.

The shocking attack was captured by CCTV cameras on the bus and showed passengers frantically attending to Mr Gallagher and trying to stem the flow of blood from his back.

Doctors initially said the injuries were life-threatening as he had been stabbed in areas of the body where wounds can lead to death.

But, after examining his injuries in more detail, a consultant concluded that Mr Gallagher’s life had not been put at risk.

Defence solicitor Mark Chambers said the assault had been carried out as a revenge attack by a man defending his mother’s honour.

The lawyer explained: “Mr Kerr had received information that the complainer had attended his mother’s door at her home and that she had been assaulted by this individual.”

As he caged Kerr, of Linwell Crescent, Paisley, for four years, Sheriff Ian Anderson said: “It is only by the grace of God the complainer was not much more seriously hurt.

“That is fortunate for you because you could be here facing a much more serious charge.

“The fact you lay in wait for your victim and attacked him on a bus in broad daylight, in full view of passengers to the considerable distress of the bus driver and no doubt passengers, is an added factor that I’ve had to take into account.”

Kerr’s jail term was backdated to May 22 this year, when he was first remanded in custody.