He hasn't been given any different work from the rest of his table and he says that he is very bored now ( danger signals ). When we queried this with the school, we were told that son instantly understands maths, but has a lovely, caring disposition and voluntarily goes around the class helping the other children. We are proud of him for this, but I would rather he be given more challenging work than be used as a junior TA.
This is absolutely shocking. Good mathematicians do often instantly understand primary maths and require challenges that broaden their maths not just more of the same involving larger or smaller numbers. I can't believe any teacher thinks it's acceptable for a member of the class to be going around helping other pupils.
I'd just keep going with what you're doing at home. It doesn't matter what level he gets in SATs, his ability will still be the same and hope that next year he gets a proper maths teacher who can take him forward. Having said all that I'd have spoken to the head about the situation - it's just not good enough.