By year three my youngest wasn't doing very well at his primary school. We knew he was a capable boy but his abilities were not presenting themselves in his school work - he was in the lowest group for English and the second from lowest group for maths. At the end of year three his form tutor asked to see us and told us he was an intelligent boy but she felt he was bored in class and she couldn't get the best out of him in class. After much thought we decided to take him out and put him into a local private school that had 15 in the class. We are so grateful to that school for what they did for him, when he joined they tested him and said he was behind in both English and Maths, but by the end of year four he had caught up with the rest of the class and was doing very well. To our delight he kept improving and got a high enough mark in the eleven plus to have got into our local 'super selective' although we didn't put it first as we preferred one of the other grammars. He is very happy and loves his school and we are over the moon with our choice of school. Trust your instincts. If you think he is up to grammar give it a go. I know of two boys who didn't get all level fives in their sats, who got into grammar and did very well in their GCSEs and are now doing their A'Levels (predicted very good grades). From your description of him he sounds a very bright boy. With your support I really do think he will do very well and don't hesitate to get a tutor to tie up any loose ends if you think it's necessary. Good luck with everything!