... at the advanced age of 87, H M Queen Elizabeth II is the most elderly monarch ever to have occupied the throne of Great ... making her eldest son, HRH, Charles Prince of Wales, the oldest heir apparent in British History.
However, Elizabeth R, is NOT our longest~reigning Sovereign, such honour - as yet unbeaten - being vested in her great-great grandmother, Queen Victoria ... who reigned for a total of around sixty-four years from 1837 until her death in January 1901, aged "only" [by comparison] eighty-one.