FWIW, I really disagree with taking away rewards once they have been achieved for a specific thing.
A Headteacher's award is a big deal, and it is fantastic that the school recognised how well your DS did by not having an accident yesterday.
He should be really proud of himself.
IMO it would be a huge blow to his confidence and self-esteem to take away something that was given in recognition of this achievement.
The school gave the award, so as a parent I wouldn't intervene and suggest it should be removed.
I can understand the behavioural nurse advising you to follow through 'threats' with regard to instating consistent boundaries for behaviour, but are these toilet accidents deliberate, and do you regard them as bad behaviour?
And if so, have you been advised to punish your DS for them? (Removal of award constitutes punishment IMO)
Just interested in how this behaviour is perceived by the behavioural nurse, by the school, and by yourself, as it would obviously be helpful to your DS if you all had a consistent approach.
Sorry, Whoops, but I agree with the school on this one.
I can see that you're p'd off with the teacher, as you expected the school to support your decision re the award, but I can see why they didn't, and I think they made the right decision on this occasion TBH.