It is very important for society that children from all walks of life are educated together and I believe the most important thing for comprehensive schools is that they retain this mix of children.
In my area local secondary church and private schools already threaten the excellent social mix found in our primary schools. I believe the proposed West London Free School will just be one more way in which middle class families will be discouraged from sending their children to the local comprehensives as these families are more likely than others to be attracted by the ethos of the new school. However what most parents really want is a good quality local comprehensive catering to all.
As long as local comprehensives can retain their mix of pupils I believe they are the best way of educating young people to take their place in a society that values all types of achievement. Comprehensive schooling is not one-size-fits all, it can be a sophisticated approach which allows for diversity, meets different needs and aspirations and encourages individual aptitudes.