Collection of over a hundred letters, August 1916 - November 1918, sent home by three brothers from Swansea during the First World War. Richard, Gabriel and Ivor Eustis sent the letters to various family members while they were serving in different theatres during the war, including Palestine, Saxon, Egypt, France and Italy. A book about the letters/family was published as, Having a Go at the Kaiser: A Welsh Family at War (2018).

Papers accumulated during the course of Julian Franklyn's research into the recruitment, training, equipment and campaigns of the Welsh Horse (Lancers) Yeomanry, with particular reference to Lord Kensington's role in them, including many records that were originally created by the Welsh Horse itself and first accumulated by Kensington as its commanding officer.