The UK system is unique for selecting kids at a very early age. At 11, kids take a test to enter super selective public schools: http://en.wikipedia.org/wiki/Grammar_school. In some parts of UK only 2% of the 11 year old make it in. For those who don't make it, their only chance to go to top universities is to pay for expensive private school.
Not quite. Comprehensive (non-selective) schools are the norm and have been for many years. Grammar schools only remain in very few areas, where the local authority has chosen to keep them. For the majority of the country, there isn't a local grammar school.