William Kirkpatrick, the eldest son, became a cadet in 1771, was appointed ensign in the Bengal infantry on 17 January 1773, lieutenant 9 April 1777, captain 3 April 1781, and major 1 March 1794. He was Persian interpreter to Giles Stibbert, who was commander-in-chief in Bengal in 1777–9 and 1780–5, and prepared a Persian translation of the articles of war (printed 1782). Afterwards he was resident with Mahadji Scindia at Gwalior, and served on Lord Cornwallis's staff as Persian interpreter in the Third Anglo-Mysore War of 1790–1.