Much depends on the point at which we decide that RP came into existence. William Gladstone, who was PM for four different terms in the late 19th century, went to Eton College yet his pronunciation gave away that he was from the North of England and his speech was criticised by RP speakers in the early 20th century.
Definition of vane. 1a : a movable device attached to an elevated object (as a spire) for showing the direction of the windb : one that is changeable or inconstant.
What is a Weather Vane? According to The American Heritage Dictionary of the English Language: weath'-er-vane, noun, a device for indicating wind direction. While some purists insist that the proper term is wind vane, we prefer the historically accepted and most used weather vane. We also believe that a picture would best describe a weather vane, so here goes.... There are only two basic rules that must be followed when designing a weather vane: