@gingdottwit I am less confident in Alton Towers due to limited historical data for that park. Turnout is also linked to other factors such as weather which cannot be predicted this far in advance.
@gingdottwit If you click on the days for the 27th/28th you can see what the wait times were, and that they were much higher than usual. While I can't say for certain the reason, often towards the end of school terms are when a lot of school trips happen to theme parks (as a sort of reward).