Official statistics on the number of hours that teachers spend in front of a class have a striking similarity to icebergs. There is always a lot that is concealed.

But judging by the OECD statistics, Hungarian primary teachers have the most leisure time, being required to teach for only 551 hours a year in comparison with the international average of 791 hours.

At the secondary level it is the famously industrious Koreans who actually have the lightest teaching load, being required to put in only 456 hours. That is 244 hours less than the OECD average and almost exactly half of the total clocked up by the hard-working Dutch.

Teachers in the UK also have above-average teaching loads, although their reported working hours - in school - are not unusually long (800 in primary and 740 in secondary). By comparison, secondary teachers in Italy have a relatively easy life, although their low salaries reflect that fact.

But for some unexplained reason, Italian children aged 12 to 14 have to spend more time in the classroom than any other OECD pupils. They put in 1,105 hours a year - nearly 500 hours more than their teachers.