My step son might be being kept back a year in school! ADVICE PLEASE?

his mum says its due to his confidence? do they keep you back a year for social problems, he walks around in a daze, never listens, and takes ages to do anything! and it seems to be getting worse the older he gets he is 5!!! would he be kept back a year through out his school years? surely this is not good for ids to be the the oldest in the year by a year??? i have tried to talk t her about it but she just says that im saying she is being a bad parent! which im not doing im just thinking about whats best for him, I do think adhd could be a possibility! anyone been in this situation??? thank you in advance. ( its a british school)