Grammar or Comprehensive schools

As the Tories look into expanding the number of Grammar schools, the Labour Party shadow education minister has said that the overwhelming evidence points to the benefits of a comprehensive schooling where pupils of all abilities are lumped together. She would say that wouldn't she.
The rump of her argument is that it is discriminatory and therefore unfair to test children at 11 years, thereby subjecting those who fail to a lifetime of stigmatization and under achievement. Almost all those who support this, including the socialist teachers of the NUS, fail to mention that children can be re-evaluated at a later date thereby allowing them to pursue a more academic education.
What I'm sure she really means is that the move to more Grammar schools will further the discrimination of TEACHERS. Leftie teachers will fear that there will be a stigma attached, not to the children, but to the teachers that fail to get positions in a Grammar school and have to settle for second best, teaching in a Comprehensive.