There are 3,500 more teachers since last year, according to official statistics and 36,200 more teachers working in schools than there were in 1997.

Welcoming the news, the Government put part of the success down to better pay prospects. From this September an experienced teacher in inner London could earn up to £40,000 with Heads being able to earn over £100,000.

An increase of 22,300 support staff this year is also helping teachers to focus on the core business of teaching, said the Government.

Jacqui Smith, Minister for Schools said: “We have made significant progress in meeting our commitment to limit the class sizes for five, six and seven year olds, this year the number of classes that contravene class size regulations has fallen.

“However, there has been a small rise in the number of classes – with valid exceptions – where numbers exceed 30 children. The Government has a range of legal powers that can be used to ensure that schools fulfil their legal obligations on class sizes, and there should be no doubt that we will not hesitate to use them where necessary.”