Any form of payment by results assumes that it is the efforts of a single teacher which produces the specific outcome. But who is responsible for the grade an individual student gets in maths? Their maths teacher? Their maths teacher from previous years? The primary teacher who taught them their first sums?
Good schools work collectively. They recognise that everyone's work supports everyone else's. Good teachers are those who work with others.
If, David Blunkett, teachers are "our most precious asset" then accept that they need to be paid properly and that performance related pay is a cheap gimmick which will result in further demoralisation.
Will Reese. 116 Rosslyn Avenue. Coundon. Coventry