It cost me nothing to join; I just had to provide a police clearance certificate and two references. Once these had been checked, I started getting work. The biggest advantage of an agency is the ready-made infrastructure. I don’t have to pay to advertise my services or handle enquiries at all hours of the day or night. I also get a steady supply of work which I could not guarantee if I was on my own. I pay commission, of course, but when I did the sums I found that it is cheaper to pay the agency than to try to organise it all myself.

I admit that my first reason for tutoring was financial, but I soon found that there is something intensely satisfying about seeing someone improve, and knowing that you are responsible for it. I briefly considered becoming a full-time teacher, but didn’t think the holidays would compensate for the long hours and pitiful pay.

So I have the best of all worlds. I get the satisfaction of teaching, without the discipline problems inherent in the school environment, and better pay than if I was working in a school. I also choose when and what I teach, which lets me organise work around life.

Who wants private tuition, and why? The why is easy. In the current state system, teachers don’t have enough time to give all their pupils the education they deserve; it’s hard enough trying to keep them under control and motivated. There is simply not enough time to take care of those who are struggling, or the bright sparks aiming for an A*.

Broadly speaking, tutees fall into two categories: those who need immediate help with a specific problem, and those who want someone to help them keep up with their classes and stay on their toes. Private tuition also gives pupils undivided attention. There is no embarrassment about putting your hand up in class to say you haven’t understood something. I also get a lot of enjoyment from thinking up new ways of teaching someone to understand something they have trouble with. You have to really get inside their head and try to look at the problem through their eyes.

A lot of the time is taken up building up your pupil’s confidence. I had one boy who was terrified of reading out loud in class. He would get terribly nervous and short of breath. We worked on his breathing and posture, then looked at how to use commas and full stops to guide his reading. It wasn’t easy for him but he kept on going. I will never forget the look on his face when he told me he got a star for reading - or the cake his mother made me that gave me food poisoning!

Whether it is someone who has slipped behind or, as with one of my pupils, someone who has raced ahead and wants an adult to bounce ideas off, a private tutor can be there when a teacher is not.

Some people say private tutoring discriminates against the poor. I disagree. My pupils’ families have two things in common: they all want to give their children the best chance in life, and the state system doesn’t meet their needs. People are free to spend their money on whatever they want to. I teach pupils whose families have to scrimp and save to afford tuition (one father has given up smoking to support his son’s “private tuition habit”, as he puts it), as well as those who don’t notice the cost.

Both receive the same benefit.

Tutoring is worth the effort. But there’s one thing worth knowing about: how to get rid of the endless cups of tea you are offered. The potted plants at my pupils’ houses have never looked so well.

Tom Rogers, who tutors in north London, has business degrees from French and English universities