Isn't 6-7 old enough to get changed on their own? My kids aren't that age, but we certainly used to get changed at swimming on our own from this sort of age and younger (hence situations where we got home and mum realized we hadn't put our knickers on!, or left half our clothes at the pool). I am sure in the past there was never any notices, because there was never any need for them because children were getting changed on their own well before it was ever an issue. Don't 6-7 year olds go swimming with school and get changed independently?