Some of the existing grammar schools I am aware of have already been expanding their numbers both in year 7 and in the sixth form.In my dds grammar school the school is adding another 29 girls to the school in years 7 to 11 and this will continue for another 3 years.The sixth form has also increased its capacity so there will be at least another 200 girls in the school once the process is complete.This is due to a number of factors including pressure for places,increased capacity and reductions and changes in funding.
Another 750,000 school places are needed according to a recent report.The pressures for expansion in existing Grammar schools will continue.
Does making them selectove particularly increase the cost?
No, probably not. But they may increase the inequalities in our society that the referendum has highlighted
It's not about financial cost - it is a high social price to pay and a retrograde step - most civilised societies have never segregated by ability and those that have are generally in the process of dismantling that hierarchy rather than rebuilding it.
I and my siblings and their other halves are all the product of comprehensives.None have looked to go down that road for their children after their own experiences in different comprehensives if they have a choice.