League tables were introduced in England and Wales by the Conservative government in 1993 to record publicly the best and the worst performing secondary, independent and private schools.
Primary school tables, which were first published in 1996 are based on exam results, truancy rates and the level of educational provision. In Scotland, the publication of exam results for public and private schools is categorised by local authority area rather than by school. There are no league tables for primary schools.
A similar system operates in Northern Ireland where "performance information data" are published annually and grammar and state school results are listed alphabetically in each local authority area. The information is not produced for primary schools.
Before the introduction of league tables, subsequently enthusiastically adopted by Mr Tony Blair's Labour government, most teachers in England and Wales feared the worst. Schools achieving high positions would be able to pick and choose pupils condemning children in high areas of unemployment to 30-plus class sizes and poor prospects in adult life.
While there are no statistics to chart the ability of schools to "cherry-pick" pupils, the National Union of Teachers argues there are countless examples of schools being unfairly condemned by parents as a result of their performance in league tables.
The British government believes parents have the right to choose which school their children attend and that poorly performing schools should be publicly recognised as such, but the NUT says league tables do not reflect the real educational performance of schools.