A common name for pubs in Britain is The Royal Oak of which there are nearly 500. They are named after the oak tree in the grounds of Boscobel House in which King Charles II is said to have hidden to evade Parliamentary forces hunting him after his defeat at the battle of Worcester in 1651.
And this is the tree... or rather it isn't. The original oak tree was so damaged by souvenir hunters after the Restoration that it died. However, a sapling was grown from the original and this is the tree that now stands in the grounds, so the daughter of the Royal Oak if you will.
In turn this too has been badly damaged by lightning strike but a sapling from it was cultivated a few decades ago and that is the tree that stands just behind it.
By the way, when Charles hid in the tree the whole area was thickly forested... otherwise it might have been a somewhat obvious place to look for the fugitive!