However, this is not always the case. Switzerland has faced teacher shortages despite relatively high pay and Hungary has an oversupply despite low salaries. Britain suffers shortages despite a 70 per cent increase in teacher salaries during the past decade.

In most OECD countries teachers’ relative earning position compared to other graduates has declined in recent years. When relative earnings fall, resignation rates rise, particularly for male teachers and those with higher qualifications.

A number of countries experiencing shortages have concentrated salary rises for teachers in the early stages of their careers. But this has created other problems. In the UK, as in Denmark, New Zealand and Australia, teachers can reach the top of the salary scale within seven or eight years.

But it is difficult to improve on their pay and conditions after this, which may make it harder to persuade them to stay on. “In effect, the message is that teaching is not a lifetime career,” said OECD economist Paolo Santiago.

The UK has used one-off payments such as “golden hellos” and top-up salaries in shortage subjects to recruit more teachers. Performance pay is cited by the OECD as a measure to attract quality staff. But this can add to retention problems. In Sweden, salaries are negotiated when teachers are hired. However, schools have experienced a huge rise in teacher turnover as staff can only better their terms and conditions by changing schools.