Research, published by recruitment agency Select Education, and based on data produced by the Department for Education and Skills, shows that the number of overseas-trained teachers and instructors without qualified teacher status has risen from 2,500 to 12,300. There has been an increase of more than 32,000 teachers in state schools since 1997, but that only 3,000 of these were full-time and had qualified in the UK. Another 13,000 were qualified part-time teachers, and the rest were unqualified.

Bob Wicks of Select Education, said: “Schools are taking imaginative steps to ensure that, despite continuing shortages, suitable staff are available to take classes.”