A professional mountaineer who has led school parties abroad and been a Duke of Edinburgh Award assessor was jailed for twelve months after pleading guilty to causing serious injury by dangerous driving after dozing off at the wheel.

After taking a 30-strong party for an overnight trek on Snowdon Jake Tomkinson, 28, of Rowen, Conwy, was within a few miles of his home when he dozed off for “for two or three seconds” according to his QC, and hit a cyclist when his VW Polo drifted to the wrong side of the road.

Judge David Hale said at Caernarfon crown court, where he turned down a plea for a suspended sentence, that Tomkinson had already stopped twice and knew he was tired.

The judge accepted that Tomkinson was riven by remorse, had admitted his fault immediately and had given first aid at the scene of the accident at Talybont in the Conwy Valley where the cyclist had crashed into the windscreen. The victim, Mr Gareth Evans, was himself a keen cycling, surfing and fitness enthusiast.

The effect on Mr Evans, a family man, bricklayer and builder, had been “devastating”, remarked the judge. Tomkinson was banned from driving for two and a half years and must take an extended re-test before obtaining a full licence again.

“You should have stopped and had a nap – there were two opportunities to do so,” the judge reminded Tomkinson. “You were tired, you knew you were tired.”

Ryan Rathbone, prosecuting, said the accident happened at 9am last June. The trek on Snowdon had lasted from midnight to 6.30am and the evening before Tomkinson had five and a half hours sleep. The defendant had “drifted off” in his girlfriend’s yellow Polo and Mr Evans, 54, on his £1,500 bike, had serious injuries including fractures to his collar bone and ribs, and an injured eye socket. Last autumn he was still in pain and Mr Evans stated in an impact statement : “My business is affected in a massive way, I’m really struggling.” He wondered whether he would ever be pain free.

Alistair Macdonald QC, defending, said Tomkinson was a mountain leader and a teacher-instructor who had experience with parties, including youngsters with special challenges, and had gone to the Alps, Nicaragua, Costa Rica, Malaysia and Malawi. He was due to go to Morocco but cancelled the trip because of the accident. The crash was due to “a momentary lapse into sleep.”

Urging a suspended sentence Mr Macdonald said : “He’s a thoroughly decent young man, a person who has made a substantial contribution to society. As a result of a misjudgement he’s lost his good character.” He emphasised : “He’s an inspirational figure for young people who are at the bottom of the barrel – the difference he can make to these young people and the confidence he can give to them.” Tomkinson had aspirations to become a geography teacher.

Passing sentence Judge Hale told the defendant : “You were responsible for causing very serious injury to Mr Evans by the way you drove that car on that sunny morning.”

After breakfast he set off from Llanberis for home but knew he was tired. Judge Hale said : “The car is a lethal weapon.”