Fellow campaigner Stefan Richter told me about this video; it contains part of a presentation by Sir Ken Robinson and includes an observation that is very relevant to summer born children:

““We still educate children by batches… we put them through the system by
age group. Why do we do that? Why is there this assumption that the most important thing kids have in common is how old they are? …It’s like the most important thing about them is their date of manufacture. …If you’re interested in the model of learning, you don’t start from this production line mentality.”