A 58-year-old grandmother from Tenbury caused the death of a teenage cyclist in a mystery crash on a Worcestershire main road, a court heard.

Anthony Phillips died as he cycled on the pavement on the A38 near Droitwich and the cause of the accident will never be explained, Worcester Crown Court was told.

The 18-year-old mobile DJ was cycling from Droitwich back to his home in Bromsgrove with his good friend James McKnight at about 3.30pm on Friday August 10 2012, Walter Bealby prosecuting, told the court.

They stopped to light a cigarette before continuing uphill along the A38 opposite Chateau Impney.

James stopped to relight his cigarette and that could have saved his life as a Kia Picanto driven by Ruth Felce of Kyre Road, Tenbury Wells, inexplicably mounted the kerb and hit Anthony's bike. The collision threw him into the branches of the roadside trees and he suffered a serious head injury.

Felce was on her way to meet her granddaughter in McDonald's near the motorway junction and take her back to her home for the weekend, Mr Bealby said.

The same day or the day before, she had taken prescribed medication including an anti-depressant and a treatment for restless leg syndrome. Medical experts suggested these could have caused drowsiness but there was no evidence to suggest they had contributed to the crash.

She denied causing death by dangerous driving and the prosecution offered no evidence at the start of a scheduled trial. She pleaded guilty to the alternative charge of causing death by careless or inconsiderate driving.

Mr Bealby said the car had simply failed to fully negotiate a slight right hand bend up an incline and had left the road.

Felce told police she recalled seeing the two friends on their bikes at the side of the road and then all she knew was there had been "a bang or a thud." She stopped the car and ran back to Anthony, a former North Bromsgrove High School pupil, who was airlifted to Queen Elizabeth Hospital but died from his injuries.

Jonas Hankin, defending, said Felce accepted she was legally responsible but no-one could explain what had resulted in the momentary inattention that caused the "tragic consequences".

He said she had three daughters and was of good character. She was employed as a carer for children with severe learning difficulties and was working on a voluntarily basis as manager of a day care centre for the elderly.

"As a mother, she recognises the burden of taking the life of a child," he said. "It's a sentence from which she will never be released."

Judge Michael Cullum said it could have been a "double tragedy" if James McKnight had not stopped to relight his cigarette.

"We will never know what actually happened," he said.

Felce was given a 12 month community order with 150 hours of unpaid work and banned from driving for 12 months. The court heard she had voluntarily surrendered her driving licence to police the day after the accident just over two years ago.

She was also ordered to pay £1200 towards costs.