Haven't had chance to read this all through, but noted that you are talking about Grade skipping in U.K. schools. This is a world of difference from U.S schools, which have much stricter curriculum per Grade issues (I'm a Brit Elementary Teacher living in the U.S.). There really shouldn't be any need to skip in Britain, as your child should be sequentially following the N.C. at his appropriate level. Naturally there will be more kids at his level in higher Grades, so you may want to do it anyway, but the two systems are pretty incomparable. My DS6 has been recommended for a complete Grade skip here, and we are seriously considering it - if we were living in the U.K. I really don't think it would be an issue.
On the other hand, the U.S. does seem to have a better handle on 'gifted education', as a whole, with a lot more emphasis on Creative and Logical Thinking.
This might be a topic that might be worth discussing with the school, especially if you decide not to skip. Good Luck.
