Oak Apple Day in the UK Date in the current year: May 29, 2024

The story of the holiday dates back to the Battle of Worcester that took place in 1651 during the English Civil War. The future Charles II of England managed to escape the Parliamentarian troops by hiding in an oak tree in Boscobel wood. A Parliamentarian soldier passed directly below the tree but did not notice Charles. The tree was late named the Royal Oak.

After the Restoration, Parliament declared May 29, the King's birthday, a formal public holiday. It was named Royal Oak Day or Oak Apple Day in memory of the future king's escape from the Roundhead army.

Royal Oak Day was formally abolished in 1859, but is still celebrated in some parts of the country. It is sometimes referred to as Ooh look, its the King!, Oak and Nettle Day, or Shick Shack Day. On this day, people wear oak apples or oak leaves. Those who failed to do so might be thrashed with nettles or pelted with bird's eggs.

The holiday is also celebrated by working residents in the Royal Hospital Chelsea as Founder's Day because the hospital was founded by Charles II.