I personally think Grammar schools are a good idea. It makes much more sense to stream pupils by ability.
Pity it's mathematically impossible to do that within one school, and on a per-subject basis.
One perfectly valid reason for grammar schools is that kids from council houses are thieving little oiks with nits. I'm rather surprised you didn't mention it.
P.S. If you sincerely believe selection was/is based purely on ability I have several bridges you might be interested in buying.
Lol, I actually failed the selection exam (the 11 plus) to get in to Grammar school so does that answer your question regarding ability :)
To be honest though, I didn't see much point in it at the time as I lived in a borough that had grammar and comprehensive schools but actually went to school somewhere that only had secondary moderns that did not place any stock in the 11 plus exam. I only did the exam because of where I lived, not because of where I actually went to school so it did not matter if I passed or failed, I was always going to go to the same school afterwards.
And by the way, I was one of the thieving kids from the council houses who had nits :)
My point was really that grammar schools offered the possibility for the select few of us poor folk who got in to be schooled in a similar environment to that of a private school. Whether this is a good idea or not is irrelevant, what is important is that some people who make decisions (oxbridge admissions professors for example) later on in the childs life think it is.
There was a very interesting documentary about this recently on UK TV where they interviewed a bunch of people who had come through the grammar school system. I know it had been criticised since but the reality is that it did have a valid point in that however unfair it is to stream kids at 11, it gives the opportunity to those who do well to break into the sort of jobs that are normally restricted to those coming from public school. By removing grammar schools we have diminished the number of state school kids who get in to oxbridge.
Being that under the old system a great many people I know did well based purely on hard work even though they went to comprehensives being disadvantaged at that age did not really make much difference in the long run even though it might have stopped us going to oxbridge.
Those who are opposed to forcing kids though an exam in principle though will often never take the pragmatic view of grammar schools I do though and I understand that, its just that the private school system does exist and there is no getting away from that. Most private schools have an entry exam at 11 so having something similar in the state system just seems to make sense to counter this.
I am actually considering saving money for my kids now (just before the first one is born) in order to maybe give them an opportunity to go to a private school later on. Of course in 18 years though I will probably need every last penny just to help her get to any university.