I have to say that back in the hippy 70s the borough I grew up in had a great scheme to attempt to level the playing field. The Primary School Heads nominated which pupils were best suited to the three different sorts of schools and four pupils who were borderline direct grant / grammar and grammar / secondary mod, who then went off to a gorgeous country house where we spent the day playing, building things with wooden blocks, doing puzzles, some tests, having discussion groups about things like whether God existed
I know!!! but I am sure I remember right, juggling and learning navajo, actually I made the last two up, I think... I just remember it being enormous fun. They then decided where we fitted, it was called the Thorne scheme and though I remember being quite amused by it all, it was subsequently endorsed by the Plowden Report
"The Thorne system, so called from the neighbourhood where it was first tried, was designed to take account of these two observations. An initial quota of selective places is given to each primary school and is generally based on the results of the previous three years. The accuracy of this figure for the current year is checked by a careful investigation of all borderline pupils undertaken by a panel of head teachers. A further check is provided by the feedback of information from the secondary schools to the primary schools. The purpose of this system is to avoid distortion of the primary school curriculum by dispensing with an externally imposed test. It achieves this object without loss of accuracy. It is acceptable to teachers and parents and has led to cooperation between primary and secondary schools. We are impressed by its advantages and hope that authorities which continue to use selection procedures will study its merits."
The section of the Plowden Report on selection is itself interesting since written in 1967 it proves what goes around comes around.www.educationengland.org.uk/documents/plowden/plowden1-11.html
What I do know is that my peers at the direct grant grammar came from all sorts of backgrounds, and it enabled girls from working class backgrounds to go on to university and successful careers.