
Even though all the celebratory stuff happened last weekend to work in with the Platinum Jubilee of Queen Elizabeth II, the festivities for the official birthday of the British Monarch are usually held on the second Saturday in June, the June birthday custom having been brought in by King George II in 1748. The real birthday of the current British monarch is April 21st, and her duties are not the same as those of her ancestors.
https://www.goodto.com/royal-news/queen-elizabeth-two-birthdays-uk-australia-559015