Just found this fascinating thread, terribly sorry to join the discussion so late.
@PinkElephantsOnParade:
Re: first-come first-served at highly sought after schools. As notrightnow points out, this method is effectively an assessment of the parents' knowledge, organizational skills, and the extent to which they value their children's education, among other attributes. If you're going assess the parents anyway, you might as well just do a full-blown interview of them and explicitly pick the attributes you're looking for.
Re: the school which allocates by lottery at 4+ and manages out those who aren't keeping up at 7+. I'm afraid I don't understand your horror. Would you prefer that they not offer a pre-prep and only select at 7+? Or would you prefer they adjust standards so that all 4+ entrants can remain?
Re: children who are not keeping up being asked to leave, and further hurdles at 11+. Actually, it doesn't end there. In another thread I asked why a third to a half of 16 year olds at City of London Girls School and South Hampstead High School leave for other sixth forms. The private feedback I've gotten indicates that at least some, and perhaps "many", are managed out at that stage as well.
@montysorry:
Re: your predictions of Y6 results in Reception. To what extent were your predictions correlated with attributes of the child and to what extent attributes of the parents, and to what extent was it not possible to distinguish attributes of the child from attributes of the parents, i.e., the attributes of the child being highly correlated with attributes of the parents?
Re: not sending a child to a school at 4+ if you are sure they would not get in at 7+. You indicated that, at Reception, the "vast majority" were "wait and see" or better. So only a few parents could be in a position to know their child wouldn't get in somewhere at 7+. The "vast majority" would seem to be justified in hoping for the best.