According to the unimaginative left you can only have Grammar schools with a single 11+ exam design. There are no possible other designs that allow academic individuals to be schooled in a school focused solely upon academic achievement. And that's Hitler so no to Grammar schools.
Well no. We can easily design a sensible Grammar school system.
Firstly the whole test is a massive pain and you do have to spend ages preparing for it. It would be much better if the primary system started to stream earlier and individuals moved up and down between the schools.
So you then have a virtual comprehensive system with streaming.
But to get anywhere further down the achievement scale you have to spend more resources on the middle layer than you would on the high academic achievement grammar schools.
Grammar schools should have class sizes of 40 because you can efficiently teach cleverer kids in that sort of group size. Class sizes up to what you have in university would make it less of a leap. That then allows you to get group sizes down to 15 or lower at the other end of the scale and make a real difference.
The failure of comprehensives was simply to merge the academic grammar schools into secondary moderns to make the averages look better. They never fixed the problem. They just masked it.
That's the real problem - why did the secondary modern concept fail the middle tier so badly?
But despite that the leftist approach of 'all must have prizes' and "let's bring half the nation down to the average' (I know this is impossible, its called a joke) is insane. The Tories have been somewhat critical of the 11-plus exam, but not the funding inversion. So if you want good policy come to this blog.
You would have thought this was obvious. It's the same division of labour point the Adam Smith made - two specialists combined will always outperform a set of generalists.