Named after a pub called the Royal Oak, which gave the station its name in 1871.
The original Royal Oak was a tree at Boscobel in Shropshire where the future Charles II hid from Parliament's soldiers after the Battle of Worcester in 1651; he later told Samuel Pepys that a soldier passed directly below him. After Charles gained the throne, many pubs took the name in commemoration. The pub here is now The Porchester.