This is a picture of an **'oak apple' gall described below.
Oak Apple Day or Royal Oak Day was a formal public holiday celebrated in England on 29 May to commemorate the restoration of the English monarchy, in May 1660.
In 1660, Parliament declared 29 May a public holiday:
"Parliament has ordered the 29 of May, the King's birthday, to be forever kept a day of thanksgiving for our redemption from tyranny and the King's return to his Government, he entering London that day."
The public holiday, Oak Apple Day, was formally abolished in 1859, but the date retains some significance in local or institutional customs. It is, for example, kept as Founder's Day in the Royal Hospital, Chelsea (founded by Charles 2 in 1681).
Traditional celebrations to commemorate the event often entailed *the wearing of oak apples (a type of **plant gall) or sprigs of oak leaves, in reference to the occasion after the Battle of Worcester in September 1651, when the future Charles 2 of England escaped the Roundhead army by hiding in an oak tree near Boscobel House.
Charles 2 of England:
Following the execution of King Charles 1 in 1649, his eldest son made a brave though misguided attempt to regain the throne. In 1651 his hopes were crushed at Worcester in the final conflict of the Civil War. Young Charles was forced to flee for his life. Initially he set out to cross the River Severn into Wales, but found his way blocked by Cromwell's patrols. He sought refuge instead at #Boscobel House in Shropshire, hiding first in a tree which is now known as The Royal Oak and then spent the night in a priest-hole in the house's attic. Charles then travelled in disguise via other safe houses before escaping to France.
Below is a descendant of the original Royal Oak:
At some Oxford and Cambridge colleges a toast is still drunk to celebrate Oak Apple Day.
Boscobel House. These days it is managed by the British Trust:
** An OAK APPLE is the common name for a large, round, vaguely apple-like gall commonly found on many species of oak. Oak apples range in size from 2-5 cm in diameter and are caused by chemicals injected by the larva of certain kinds of gall wasp in the family Cynipidae. The adult female wasp lays single eggs in developing leaf buds. The wasp larvae feed on the gall tissue resulting from their secretions. Considerable confusion exists in the general 'literature' between the oak apple and the oak apple gall. The oak marble is frequently called the oak apple due to the superficial resemblance and the preponderance of the oak marble gall in the wild. Other galls found on oak trees include the Oak artichoke gall and the Acorn cup gall but each of these has its own distinctive form.
# Boscobel House was built in about 1632, when John Giffard of Whiteladies converted a timber-framed farmhouse into a hunting lodge. The Giffard family were Roman Catholics, at a time when the religion suffered persecution. Tradition holds that the true purpose of Boscobel was to serve as a secret place for the shelter of catholics in times of need.
I actually posted this late on 28th May (10.42 p.m. WST) as I wanted to make sure it would appear early on 29 May. I will be out in the morning so wouldn't have been able to post it till late in the day.