I am afraid your own grasp of the relevant law is shaky to say the least. Your most recent post is riddled with inaccuracies.
From later this year grammar schools will be required to publish the results of selection tests before the deadline for applications. However, under the current Admissions Code this is a "should", which means it is recommended but not compulsory. Sutton is by no means the only grammar school to conduct its tests after the deadline for applications. It is not ideal but they have not broken any rules. They will, however, have to work to a different timetable for their tests for boys wanting to start in 2013.
Their letter is absolutely correct in saying that passing the exam does not guarantee a place. They are required to make that clear to parents. If the number of children passing the exam is greater than the number of places available they must allocate places in line with their admission criteria.
Note that the new admissions code merely requires schools to inform parents of the outcome of selection tests prior to the applications deadline. That could be interpreted as simply meaning they need to inform parents whether their child has passed or failed rather than publishing the individual marks.
Contrary to your assertion you cannot obtain data about the results of successful applicants under the Freedom of Information Act. That is personal information. At best you can get aggregated data, so for example you may be able to find out the average marks of those who passed. You certainly cannot find out the marks of individual candidates.
It is true that Sutton would have to respond to a Subject Access Request for the examiners comments (if any) and your son's marks. However, the Data Protection Act gives them much longer to respond to such requests than for other types of Subject Access Request. This is so that candidates in exams cannot use the Data Protection Act to find out their results early. So the school is perfectly entitled to refuse to respond to your Subject Access Request (if you have made one) until March. By the way, if the examiners have made comments on the exam script Sutton should either blank out your child's answers or copy the examiners' comments into a separate document before giving them to you, so you still won't get to see your child's answers.
You seem to persist in viewing this as some vast conspiracy by Sutton Grammar School to fiddle the results in order to deprive your son of a place. I can see absolutely no evidence of this.
Even if they were to give you your son's marks there is absolutely nothing you can do with them at this stage. You cannot appeal until he has been refused admission. That won't happen until March.