Do you have a criminal in your classroom? Chances are that, if you are a secondary teacher, at least a couple of the pupils you teach in the course of a week will have a criminal record, although you may not know who they are. In recent years, between 1.5 per cent and 2 per cent of 10 to 17-year-olds have acquired a criminal record for the first time each year - on top of those who already have one.

Indeed, government officials estimate that some 700,000 youngsters gained a criminal record between spring 2000 and early 2008. And these figures don’t cover every child who has been in trouble with the police, since they only include convictions, reprimands and warnings, and not those given out-of-court disposals such as fixed penalties and penalty notices for disorder, which can be handed out for a range of offences.

Fortunately, the 2007-08 figures represented a 10,000 drop from the record number of 103,955 dealt with the previous year. But it is a lot higher than the 84,499 who were caught transgressing in 2000-01.

Of course, most criminal behaviour is silly rather than serious, and the majority of youngsters will grow out of such behaviour - only, in some cases, to find that they are left with a millstone round their necks which will have to be confessed to every employer and voluntary group they work with throughout the rest of their lives.

In some cases, it will also mean that foreign travel is more difficult, as they will require expensive visas - for instance, to travel to the United States

John Howson is a director of Education Data Surveys, part of TSL Education.