Just composed an erudite essay (!) only to have my computer drop the wi-fi connection and my efforts were in vain. I'll try to remember that wot I rote 
When I started school in the early fifties we had all sorts of holidays, religious and secular, as it was a village CofE school. On Holy days such as Ascension Day, All Saints Day etc we would join an early service in the church next door, or the vicar would conduct prayers in the classroom, then we'd have the rest of the day off. On Empire Day, May Day or on ancient notable dates such as Quarter Days (it was a farming community) we'd have a half-day holiday, and on battle anniversaries such as Trafalgar Day, Relief of Mafeking or Ladysmith, VE day etc and patron saints days we would have special lessons about the event. I'm afraid I've forgotten most of them but we seemed to have a lot! Childcare was never a problem with these odd holidays as very few mums worked and children of those who did were looked after by other mums.
I think it was the Conservative government in the early seventies who did away with the variable date of Whitsun and gave us the Late May Bank Holiday instead, closely followed by the Labour Government who gave us the fixed May Day, also known as Labour Day on 1st May in communist countries.
