Part of the problem there is that parents wind their children up and set expectations and it's about how the parents think it's going to go.
So if the parents wanted staggered starts in and then we're told they couldn't have that. And the schools attitude was 'well it wasn't our choices', those parents are going to be overly anxious and the kids feed on it. The parents effectively set their kids up for that.
Whereas if the school say, 'we find that actually a full time start to get it over and done with, with the fewest number of distractions is the way to go', they set the parents expectations and reassure the parents. So the parents are less anxious and the kids have less to feed off.
Thus the issue is one over psychologically preparing the parents and not really the children at all. Children who are secure with their parents will trust their parents and look for their reaction. The kid whose parent is dramatic over leaving them is the kid that's most insecure.
Genuinely there were not many children at all who found it difficult for my son's year. My son was fine despite a lot of the others going to nursery for much longer days and longer weeks. DS was at a disadvantage because of this.
And of course it helps if the kids know at least one other kid going and you sell it as playing with little Johnny all day.
You don't have conversations about how you aren't sure if little Emily is ready for school in front of little Emily or her friends though.
That's also why the phased start will show up well in research but it's not necessarily the phased start that's doing it, because other schools genuinely find the in unphased start works too. Because it's all about setting the parents expectations and reassuring the parents so the kids have theirs set well because it's about psychology rather than the actual method you use.
That's why you got so upset about it and the head saying what she did privately only has fueled your anxiety between the changing system and set you up to resent those three parents. The head has a lot to answer for here - she should have reassured you rather than blaming others. Your anger at the change really won't have helped the vibes your son was getting when he started school will it?