It is outlined briefly on this site at http://www.Elevenplusexams.co.uk/school ... nt-11-plus
My understanding (which I expect to be clarified by others) is:
1) Results are sent to headteachers a few weeks before parents get the results.
2) The headteacher looks for any fails that are out of character (only the head really knows how they do this and Kent may have more guidelines)
3) Head can present evidence (to the panel set up for this purpose) of out of character student's performance and the essay is also reviewed - they may recommend that some are passed and the evidence is submitted - I gather if lots of requests were submitted it would be questioned so the review process is used sparingly
4) Head is informed which review requests have gone through and which were rejected
5) all parents are informed of Kent pass/fail but not necessarily there was a review, not certain if they find out if they ask for a breakdown.