I don't think a perfect test exists either, but I don't see how the test my son took discriminates in favour of middle class children.
The English and Maths papers were based on what is covered in KS2, and the NVR/VR test is just that.
I think supportive but non English speaking parents would have children that cope ok, I can't see how it would be any harder for them to do well than it would in a comp. If they were that supportive, they would learn enough English to get by, or they would get their children to translate things they need to know.
Seeker, why do you have such a problem with middle class families? By your definition, I am middle class, although it certainly doesn't feel like I am. I have a much bigger problem with those parents that will happily send their child to my son's school, but would have had no problem sending them private if they hadn't got in. There is no way I could afford private, even on a generous scholarship.
Grammar school isn't just about social mobility in the way you come across as thinking it is, it's about teaching children in a way that suits them best and enables them to fulfil their full potential. Why do you seem to think that GS shoudl be reserved for the poorest families only?
Anyone that can't afford private school, either prep or secondary, should have equal right to apply to grammar schools.