Here is an article about the dreaded moment when you find out about your kids' secondary school allocation. Isaac passed the eleven plus so gets offered a place at Calday Grange Grammar School. The article I linked to is mainly about the majority of schools outside the grammar-school system, but it's still a nervous moment to check that you obtained the intended result.
How best to allocate schools to children, in the presence of their (or usually, their parents') preferences? I don't have an strong opinion, although lots of people have theirs. The way German kids get into gymnasiums (equiv of grammar schools), which is done by agreement between parents and primary school teachers, seems good, if you can restrain the excessive demand (which I gather is something of a problem).
(added later:) Many criticisms of the current system seem shrill, for example this one, an editorial in the Daily Mail. Certain pupils are said to be "condemned to third rate comprehensives... a life-sentence to underacheievement", also note that lottery-type systems have "scattered middle-class pupils far and wide, breaking down the critical mass of talent on which our best schools depend to serve pupils from every background." (this what lotteries do, and it's the entire point of them. I don't know whether talent has a "critical mass" effect, although disruptive behaviour in schools probably does have such an effect.) The article seems to be in favour of the grammar school system, but doesn't quite say so.