My ponderings - do feel free to disagree.
Can you get access to a developmental pead - tertiary centre (2nd opinion process via GP with NHS or even pay and go private!) to show these docs to?
Adhd diagnosis dependent on behavior present in ALL environments - now you have proof it IS present everywhere. I'm not sure re ASD or other diagnoses - for those parental/developmental history carries more weight.
Either way I'd take these to medical professionals outside the immediate circle of local professionals (TAC = team against child, CAF= conspiracy against family) & see if it changes their medical opinion of your child's behavior.
I think I'd spend money on an independent medic before a lawyer as once you have a clear diagnosis from a respected centre of excellence it becomes proportionally much harder for school/LA to be totally stupid and gives you options. A diagnosis letter + this info equals instant death for LA at Tribunal no matter what legal backing you have (my experience of Tribunal Panel was that common sense counted for a lot). I'd be asking for somewhere out of borough in part 4 of any statement.
I suppose my reasoning is that no matter what games, or the provocation, the school etc plays we as parents have to stay totally focussed on outcomes.
You know now beyond any doubt that these barstewards done you wrong big time, & I always think parents are best off keeping their powder dry until any ammunition you can be reviewed by someone independent, or corrupt profs ALWAYS seem to find a way to wriggle out of it no matter what they get up to.