"there are parts of the country which are not fully selective, just the odd super selective, and we know the poor kids don't get into them fairly either."- Which is why I am in favor of a fairer system. And all anyone else is saying a) lets keep wealth by selection, b) the unfunded un-achieved utopian, lets make all schools good schools
unexpsoc
"the country with the most successful system (Finland) has no selection whatsoever"
What is your definition of success and should we impose it on the UK whether we want it or not? Finland has a lower GDP per capita than the UK, is that success? UK has two and a half Nobel laureates per capita more than Finland, is that success? Are you willing to impose higher taxes to pay for Finland's more expensive system? Banning private schools will also cost a LOT of money, so expect a lot more tax!
Finland's system strives to make everyone equal around the average, they help all up or leave them to float down to that level. So we would have more social mobility at the expense of high achievement. The math in a typical secondary level Finnish classroom is not particularly rigorous or advanced, the topics covered in most classes are not difficult.
Finland doesn't teach pure maths at secondary, it teaches what the UK would call functional maths, coincidentally identical to how PISA measures maths, so they are essentially tutoring for the test. The UK has parents with a desire to maximize academic ability not dumb it down. How is that success?