@Piggywaspushed
The longer holiday is a red herring for private schools ; the longer lunch produces the longer day.
Dd used to have 3-4 weeks extra holidays and a much longer lunch break.
Her independent primary timings were:
Infants - 8:30am to 3:30pm
Juniors - 8:30am to 3:45pm
Where I work (state infants) the day isn't that much different at 8:40am to 3:20pm, and we have 10 minutes less lunch. The private also had assembly daily which the state infants doesn't.
DD's private secondary was 8:30am to 3;30pm
The state secondary she moved to for sixth form did have a shorter day: 8:30 to 3:00pm but has half the time for lunch as the private school did.
Not all private schools have much longer days in my experience.
Our infant school children couldn't cope with a longer afternoon. They are tired (for more academic stuff) by the time they go home already.
And many already do sports, music, hobbies etc outside of school as it is.
A longer school day could cause issues (numbers reducing and therefore loss of income, leading to potential for closing or loss of employment for staff) for providers of other after school clubs, for after school childcare providers, groups such as Rainbows/Beavers, etc.