We have a national curriculum but no text and no work comes home. It makes it really hard to know where they are. Could you find out what is happening with the kids who he wad with last year (was he just in a 3 years ahead class or was it a special group?). Also can you insist on seeing the test given? That way you might be able to work put the level. Sounds like somebody is having a panic attack about what to do with him when he finishes maths 3 years ahead of schedule.