I have to admit I haven't read everyone's post - so apologies to anyone who has also already said this.
It seems to me teachers feel that the NC Levels at KS1/ KS2 SATs already give relative rankings approximately.
Teachers also argue that they have a great deal of data on performance of individual children.
Parents posting on this seem to be saying that they'd like to know how their child is doing nationally (data that a local school might not hold initially) and often do not understand detail on their child's school performance in core subjects.
Schools should be more proactive - identifying earlier those pupils who are not achieving the notional attainment targets for that year and getting them extra help. It would be a huge improvement if teachers could be comfortable enough to openly discuss this with parents, possibly sending home extra work, hosting workshops to help parents understand what they can do, etc....
Our school is woefully slow to openly tell parents a DC isn't doing as well as expected. Years go by - i.e. DD1 didn't get reading support until Y4, when it was clear to us that by early-Y2 she was seriously behind her peers in the school.
Help did come (at home & at school) and it did make a difference - but primaries need to be more proactive and notional achievement targets need to be seen as minimum performance target for pupils (with the proviso that pupils with health issues/ special needs may not be able to make 'mainstream' targets). Also it shouldn't take parents becoming 'pushy' to get help for a child - it really should be something easily coped with by effective teaching/ senior management tracking of pupil progress.
It seems if the goal is to raise standards then that challenge has to start in primary so that secondaries are not struggling to get large portions of their entering Y7 cohort 'up to speed'.
I agree that a blank statement 'You're in the bottom 10%' seems harsh, but the reality is with KS2 results that you can see what percentage scored broad NC Levels nationally, so most parents already are given this information, but possibly not as bluntly. I also think that the point is what happens next.
Telling a child & their family their bottom 10% and doing nothing to rectify this doesn't seem an effective or helpful approach. (With the obvious proviso that this excludes those children suffering chronic illness/ disease and/or those with learning difficulties/ disabilities which may preclude 'mainstream' targets) If the lowest 25% (maybe more) are going to have resources targetted at them to improve their educational standard then although it would be upsetting to hear you're not meeting standard - if this is used as a means of identifying those pupils in need of additional support/ tuition and targetting resources to them, that does strike me as a good thing. But as many have mentioned the later this kind of intervention is left the harder making positive improvements becomes. Therefore, it may be better to ensure a basic standard of pupil progress tracking and speedy intervention - so that a DC unable to subtract is helped at the time, not years later.
However, in all this hoopla nobody seems to have clearly explained what the intention of formally ranking a child against ability bands (by 10% - top 10%, 10 - 20%, etc...) is meant to achieve - and frankly why devise such a system if you have no intention of doing anything once you've generated the data (labelled the child)?