Plaintive cries for help can be found on the TES Scotland website, where teachers share their experiences.

“I’m applying for 14 authorities. My spare room resembles a mail sorting office at the moment.”

“Local council education personnel will know my inside leg measurement by the time I’m done calling them.”

“You need to phone schools direct for supply. If you wait for staffing, you’ll be skint.”

Doing general supply work, in which a teacher takes classes in any subject, can be tough, says history teacher Lauren Falconer. “A bad experience can knock your confidence. Then, when you’re meeting different people all the time and there’s no continuity, it can take a while to get it back.”

Reducing stress in other areas of life can be important, says Ms Falconer, particularly for inexperienced teachers. “In the end, I moved back home, registered with the council - Moray - and let the local school know I was available. I got a lot of work very quickly. I thought it might dry up at exam-time but it didn’t.

“If you can respond fast and don’t mind teaching any subject - which I don’t now - there seems to be plenty of work.”

That is not everyone’s experience, however, and teachers coming to Scotland from elsewhere can find the systems hard to fathom.

“Different councils do things differently,” says home economics teacher Julie Davies, who taught in England for 12 years.

“Aberdeenshire uses teleworkers. So schools ring them, then they call you.

It’s quite a good system. But other councils don’t seem to do anything; they don’t even give you details of their schools.

“The worst thing about supply teaching is you don’t know where your next day’s work is coming from. Usually they ring the day before, but I am always ready.

“My advice to other supply teachers would be to call schools if you want work, rather than waiting for authorities to call you.”

“I hear there’s a shortage of home economics teachers, but I haven’t got a permanent job yet.

There are almost as many types of supply teacher as there are systems for matching them with schools. Perhaps the most relaxed is the person who chooses supply for its flexible hours and is not seeking a full-time post.

English teacher Gordon Cairns belongs to this group which, according to the 2004 report, accounts for 40 per cent of all supply teachers. “I gave up full-time teaching to pursue freelance journalism. But I have a wife and family, so I fall back on supply teaching to pay the bills.

“In Glasgow, you phone the education office and they tell you a school is looking for somebody. After that, if you get on well, the school will call you.

“The work is out there.”

Someone who has taught full-time in Scotland has a big advantage as a supply teacher, says Mr Cairns. “You do have to be reliable, turn up on time and control your classes, though.

“I know one headteacher, who managed one day to get the last supply teacher in Glasgow but had to send him home again because he turned up drunk.”

“She is convinced that supply teachers will soon be able to set their own rates for the job, because there is such a shortage.”

The names of some teachers have been changed