Boy, 4, forced to walk home after school bus drops him at wrong stop half a mile away

But, with a job to go to and a son needing to get home from school, she pushed her worries aside - not least because of the many assurances by the bus company that the service was safe.

It was a decision that nearly ended in disaster when, on the first day her four-year-old boy Louis used the bus, he was dropped off at the wrong stop half a mile from where he should have been.

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Louis Key, 4, was left lost and distraught after the bus driver made him get off at the wrong bus stop

Louis found himself alone outside a pub and walked past a drugs clinic and then crossed a busy main road as he tried to find his family.

In the meantime, his 77-year-old grandmother Mavis Cull, who had been waiting for him at the correct stop, began organising search parties as soon as the bus showed up without Louis on board.

Somehow the youngster, a pupil at Wibsey primary school in Bradford, found his way to his grandmother's house.

But when he found it empty, he walked away and arrived, by chance, near the bus stop where a frantic Mrs Cull was co-ordinating the search.

The drama - ten miles from Dewsbury Moor where Shannon Matthews, nine, disappeared on her way home from school last month - has traumatised Louis.

His mother Helen, a telesales worker, said he had barely slept since and clings to her all the time.

Louis was travelling on the My Bus service, where drivers are supposed to have a register of every child's route, which was recently set up in Bradford.

Mrs Key, 36, said: "He is never getting on a bus like that again. I am paying someone now to pick him up every day.

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Louis with his mother Helen, who said her son has not been able to sleep since his ordeal

"I was really worried about this from the start - it seemed wrong to let him get on a bus unaccompanied and Louis didn't want to get on the bus.

"But I received so many assurances from the bus company that the bus was completely safe and designed especially to cater for the very young.

"They said the drivers knew every child personally and had a special register for each one.

"They said no child would ever be let off the bus unless the driver had personally made sure someone was there to collect them.

"I am a working mum and a single mum and, with all the assurances, it seemed a lifeline. But the first time I let him travel on it, this happened."

She added: "We are both so badly shaken by it. Louis can't sleep, he was so shocked and upset by what happened. He is in my bed every night and we lie awake - I think each checking the other is really there.

"As far as I'm concerned, a four-year-old is still a baby. If the driver thought he had the right stop and there was no one there to meet him then he should have kept him on the bus and phoned the school or me.

"You don't just let a four-year-old get off a bus and walk off."

Metro, the West Yorkshire transport authority, advertises the My Bus scheme as a pioneering service and says 150 such buses operate across the region.

It says drivers are given precise details of each child's travel patterns, including the stops where they should be collected and let off.

A spokesman for Metro said: "We would like to apologise to Mrs Key and her family.

"We have launched a formal inquiry into the incident to find out from the service's operator how one of their drivers, who has undergone specific training, has allowed this to happen."