Major John William Poston MC & Bar (1919 – 21 April 1945) (son of Colonel William John Lloyd Poston, D.S.O., and of Marjorie Blanch Poston nee Dalglish, of Barnes, Surrey) was a cavalry officer of the British Army best known for serving as the Aide-de-camp to Field Marshal Sir Bernard Law Montgomery from his North African Campaign to the final week of war in Europe.