THE mother of a teenager who died after being hit with a spade and knocked off his noisy modified motorbike said she was "disgusted" with his killer's six-year sentence for manslaughter.

Matthew Buckworth, 34, lay in wait after hearing Sonny Stephenson, 17, speeding around Guisborough, Cleveland, on a stolen 600cc machine after 9pm, and broke his skull with the blow, causing him to fall into a ditch.

Teesside Crown Court heard how the father-of-two was annoyed by nuisance riders in the town and had talked on social media about hitting the boy with a spade weeks before he inflicted the fatal blow.

Sonny had been riding the powerful machine with a 15-year-old pillion passenger after 9pm on August 27.

Buckworth, who denied murder at a previous hearing but admitted manslaughter, knew neither of the boys were wearing a helmet. Judge Simon Bourne-Arton QC sentenced him to six years in jail, saying there was no justification but there was "some degree of provocation" due to local anti-social behaviour in previous weeks.

Sonny's mother Elizabeth said outside court: "No prison sentence was ever going to bring my child back, however I am disgusted by the sentence received."

She acknowledged Sonny had been "foolish" but said he will now have no chance to make something of his life.

He had bought the Yamaha Diversion, which turned out to be stolen, for £150 weeks before and promised his mother he would not ride it that evening.

The bike had a modified exhaust - making it louder than normal - no front light, and defective rear brakes.

But the modifications did not play any part in Sonny's death, said Richard Bennett, prosecuting.

The pillion passenger, who cannot be named, told police a man came running out of an alley swinging a shovel.

The passenger heard a loud "ding" and felt pain, which could have been Sonny's head hitting his after being knocked backwards.

Sonny then slumped forwards, fatally injured, as the bike carried on before the passenger fell off.

The bike and Sonny ended up in a hole dug for roadworks and he could not be saved, having suffered a fractured skull.

Buckworth, himself an experienced biker, knew he had caused significant injury. He monitored developments in the police inquiry on Facebook and disposed of the spade.

Three weeks beforehand, Buckworth had said in a message on Facebook: "I had a spade ready last night but it (the bike) didn't come back until I got into bed."

The message was followed by three "angry face" emojis, the court heard.

Buckworth also wrote a WhatsApp message weeks before killing the boy, saying he had seen Sonny "flying around on a knackered old bike for the last two weeks till silly o'clock in the morning.

"Half of Guisborough is after him now.

"Was gunna give him the spade out the garage but (someone) stopped me."

Peter Makepeace QC, defending, said Buckworth accepted he was solely to blame for the death, and that "someone causing nuisance should not have their life taken away".

Mr Makepeace also said there had been persistent anti-social behaviour by young bikers in Guisborough, keeping people awake at night on noisy machines, and there was perception that police were incapable of acting.

He said: "This young lad will not have had the slightest idea that what to him was no doubt great fun and adventure was having this effect on other people."