Confronted with a pushy parent, whose child’s work is never good enough and who nags the child and you about it mercilessly, what do you do? Most of us, tempted though we may be to spell out a few home truths in forthright terms, smile politely and come up with something blandly encouraging.

Robin Riall takes a different approach: neither rude nor vacuous. He sets the offending parent homework. “I asked a mother who was going a bit over the top with her son to write a 20-minute essay with the title ‘Two foxes on the doorstep’,” he says. “When I asked to see it, she had to confess that she hadn’t completed it in the time. It had taken her 35 minutes.

“I said ‘That’s not really good enough’ and pointed out that her son’s story would have got more marks than hers because it had a beginning, a middle and an end, whereas she would have had her paper taken away in the middle.

“Her son was thrilled and she took the point that perhaps she was being a little hard on him.”

Robin has the luxury of setting parents homework because he is a home tutor. He estimates that about half of his pupils at any one time have fallen behind at school and need help to regain their confidence and put them back on track. The others may be studying for exams such as Common Entrance at 13, the 11-plus or Sats, or their parents may feel they need to be stretched more than is possible at school.

An hour a week for up to 10 weeks with supporting homework tends to be enough for one go, with follow-up sessions after a break if they seem necessary. A few students are emigrating or have been excluded, and their parents are paying for several lessons a day in the meantime.

Robin works for Fleet Tutors in Aldershot, Hampshire. The firm has nearly 3,000 tutors on its books, which makes it one of the biggest such agencies in the UK. There are an estimated 1.5 million private tutors in the UK, most earning between pound;13 and pound;20 per hour, although a few, with a good record of getting children into hotly contested London grammar schools, charge up to pound;40 per hour.

After eight years’ teaching in schools, Robin gave up last year to concentrate on tutoring because, quite simply, he prefers it. He works part-time but could give lessons for 40 hours a week or more if he wanted to.

“There is too much administration and too many problems with discipline in school and not enough time to teach, ” he says. “That’s my classroom experience.

“The huge advantage of being one to one is that you can look at the work the children have been doing, see where they are going wrong and help them to do it in a way that suits them.

“The pupils seem to enjoy it. A 10-year-old girl said last night as she went upstairs to fetch her mum: ‘I can’t believe that’s an hour - it feels like it’s only been 10 minutes.’ I love passing on my knowledge and I get a real buzz out of children learning.

“When you have a child who dreads maths and believes she is terrible at it, and, just a few weeks later, she says she is good at maths and she likes days at school that start with numeracy just as much as the other days, it is very rewarding.

“On the downside, the pay is appalling. How is it that people will happily pay a plumber pound;50 an hour but less than half that to a tutor? It reflects the lack of status we as a nation accord the whole teaching profession.”

As a home tutor, Sarah Donaldson from Farnham, Surrey, is on barely half what she used to earn as a top of main scale classroom teacher. But she feels the financial sacrifice is worth it.

“I have got my life back,” she says. “I used to work every evening and at least one day at weekends. Now I can arrange to go out and see people and I’m not totally worn out.

“I didn’t enjoy my last couple of years as a junior school teacher. I was doing an awful lot of crowd control. Now I’m teaching children who want to learn. They realise they’re behind and they also enjoy the one-to-one attention.

“Teaching is all I’ve wanted to do since I was 15, and it’s what I’m trained to do, and, even if the money doesn’t compare with what I was making before, it is worth it because this is teaching I find thoroughly enjoyable.”

Not all home tuition is private; where tutors are provided by local education authorities, though, they have a very different focus. Their role is to help pupils keep up to date with whatever work their schools provide, while aiming to get them swiftly back into the classroom.

“We try and get children back into school or into a new placement as soon as possible,” says Jane Dumelow, a team leader for Derbyshire county council’s home tuition service. “That would always be our aim. Inclusion is the key word.”

The reasons why students may be out of school include serious physical illness or mental health problems, permanent exclusion, being about to have or having just had a baby, or because they are waiting for a place at a special school.

The tutor, whose rate of pay per session reflects his or her grade on the pay scale, has the job of helping the child’s school to draw up an individual learning plan for re-integration and then putting it into action.

As a classroom teacher of 22 years standing, Jane found it fascinating seeing school from the other side.

“It is like looking through a mirror,” she says. “It is a very good learning experience - it makes you appreciate how hard it is for a child who has been out of school for a long time. It’s like an adult who has been out of work: they lose their confidence.

“A lot of our students won’t get up until late morning because they haven’t got anything to get up for. We try to give them back that focus. You build a very close and trusting relationship and you give them the confidence to take the first steps back into school.”

For some phobic pupils it may be just a matter of getting a book out of the school library, or even going for a walk past the school. Others might be able to manage a quarter of a lesson with the tutor sitting nearby, or a whole lesson with the tutor elsewhere on the school premises.

“You set targets that are realistic and achievable, and if you have planned everything right, things do usually go okay,” says Jane. “If they don’t and the children were not able to do what had been planned, you help them to see it is not the end of the world.

“When you succeed in getting a pupil back into school or another placement, there’s no greater high. A 14-year-old boy said to me: ‘I thought my life had gone down the pan and you have given me my life back’. I was quite moved by that. You feel you are really making a contribution.”