A quick way to assess any teacher is to ask, “Would I let this person teach my child?” For my money, John Jones, head at Maghull high school on Merseyside, easily passes that test.

He is supremely approachable and unaffected by all the attention he has received in recent years for his outstanding leadership, which has taken him across the threshold of 10 Downing Street to talk shop with the best of them.

For one thing, he likes a laugh - and every schoolkid will tell you what a good sign that is. For some minutes, he has me in stitches as he recounts how he once taught a bottom set of secondary-modern scallywags to count to thirty in French (he had a week to do it to win a bet with another teacher).

“I had a carousel projector with thirty of my holiday slides,” he explains. “The remote control was hidden in my pocket and I convinced the children that to change the slide they had to speak the number of the slide aloud in French - I told them it was a French projector.”

In the end, they had formed a queue, bending to say “quatre” or “vingt-et-un” into the fan on the projector. He won the bet.

Another thing about John Jones is the number of times you hear him say “I learnt”. Sentence after sentence starts like that, as he recounts the way he has built his philosophy and practice from his encounters with the great and the good in education.

He is, unmistakably, a scouser, but proudly explains that he also has “Everton” - his favoured team - written on his birth certificate. But as a child, he and his parents left Everton for the new town of Kirkby. And at 12, after only a year in secondary school, the priesthood beckoned and he moved to Upholland Junior Seminary near Wigan.

So how does a child of that age make such a decision?

Apparently, it was all down to one Father Finn - one of those young clerics who devote their lives to keeping working-class youngsters out of trouble.

“He took us off the streets,” says Jones. “He was a tremendous guy - a real role model. In fact, I made a life decision based on my regard for him.”

Catholic boarding institutions such as Upholland have often had a bad press, with celebrated horror stories of inhumanity and merciless beatings, but Jones says he thrived on the discipline.

“I enjoyed every minute of it. I liked sport and I liked music. They made me head boy, ” he recalls. “You went in September and you didn’t come home till Boxing Day. And they had huge expectations of you.”

Consequently, Jones says he has a “high expectation threshold” that he has carried with him throughout his teaching career.

His mother played a part, too. “My dad died when I was 10 and it was hard for her, so I had the strength of my mum on one side and the strength of the seminary on the other.”

In 1969, after seven years at Upholland, he went to university in Bangor- still on course for the priesthood - reading for joint honours in French and Latin, followed by a PGCE course. From ngor he went back to Upholland to teach and finally resolved to put pedagogy above priesthood. Thence to Ashton County secondary, which later became Cansfield High, a comprehensive.

“In five years, I’d taught in an independent school, a secondary modern and a comprehensive.”

His work in a comprehensive school convinced him more than ever of the value of “equal worth”.

“It doesn’t really matter whether you have setting or banding - what matters is that staff should have the skills to make everyone feel equally valued.”

His next job was head of languages at Aspull High School in Wigan, where he raised the profile of languages from virtual non-existence to a highly favoured option in which high-grade GCSE pass rates soared to 96 per cent.

Aspull had just 550 pupils. “The small school experience taught me that a teacher should be interacting with the same children as regularly as possible.”

The idea has strongly influenced his thinking on timetabling in larger schools, where he has favoured structures that allow pupils to have at least one lesson a day in the core subjects.

After Aspull, he moved to a deputy headship at Park High, also in Wigan. It was, he recalls, an enormous step.

“When colleagues worry that they have been a couple of years without promotion, I point out that I was a main-scale teacher for five years, then made quick progress to deputy headship. If you’re patient and work at it, the opportunities will come.”

During his five years at Aspull, he also studied part-time for a masters degree in education at Liverpool University. It was a long hard road, but his mother kept him going.

“I was determined to sit my mum in the Philharmonic Hall to see me graduate and have a photograph taken for her.” Like many of his generation, he had scorned his first-degree graduation ceremony, only later realising how much it had hurt her.

After his MEd came a two-year fellowship at Lancaster university, but even before that had ended he was heading back to school life. “I missed the day-to-day buzz,” he says.

So in 1988, he took his first headship at Rivington High School in St Helens, followed by a move in 1991 to Ruffwood in Knowsley, where as head for nine years he continued to build his reputation as a school improver.

League tables showed that Ruffwood was the bottom school in the bottom authority, with an top-grade GCSE pass rate of only 5 per cent. His success there - in boosting it to 25 per cent, but also in raising morale and self-esteem among pupils, staff and parents - attracted much attention.

Ruffwood was marked out by Ofsted as one of the nation’s most improved schools and Jones found himself at 10 Downing Street, offering his two penn’orth to Messrs Blair, Woodhead, Blunkett and Barber.

Since Ruffwood, he has been involved in a number of government taskforces and consultation bodies, including seminars held by the prestigious Ditchley Foundation. He has also worked alongside such luminaries as the US attorney-general, Janet Reno.

But he is never blase about his new-found educational prestige. He recalls passing the Downing Street security gates, watched by scores of curious tourists.

“I felt so grateful - to the youngsters, governors, parents and staff who had put me there.”

It was when he emerged from that Downing Street meeting that he began to consider his future - whether to stay at Ruffwood or find a new challenge. Finally, he opted to move to Maghull High last September. Though just two miles from Ruffwood, it is really a world away.

What appeals to him, he explains, is that Maghull epitomises the average school - with top GCSE passes a little below 50 percent. For Jones, it represents a new kind of challenge.

“I wanted to see how far you could take an average school,” Jones remarks.

So far, he has done a lot of listening and is full of praise for his students and staff. And some important things are already in place - not least the good humour shared by Jones and his colleagues. During the interview, his deputy jokes about the copious space needed in the TES to cover a career with so many twists and turns, but his colleagues probably don’t know the half of it.

Most likely they are not aware that as a student-teacher their head played soccer for the Welsh Universities team- also as a semi-professional for Kirkby Town; nor that he used to moonlight as a singer while he was deputy at Park High - offering patrons of the likes of North Sale Cabaret Club renditions of hits by the Beatles and Buddy Holly.

His guitar rarely comes out now, though he does still play rugby union and boasts of a few broken ribs while playing for Leigh in Dublin last year.

These days, out-of-school life mostly revolves around his family. His wife is a primary head (“We discuss primary-secondary funding over the cornflakes,” he quips.) His two younger children, Ben and Alex, are both at his wife’s school, while his older daughter, Jenny, is 17 and busy preparing for A-levels when she is not riding Sapphire, her horse.

The governors at Maghull have netted themselves an all-round good egg, it seems. And like Jones himself, they have every reason to look forward to the years ahead.