Andrew Barrie MOTION is a third cousin of Sir Andrew Peter MOTION (born 26 X 1952), Poet Laureate from 1999 to 2009. Their respective great-grandfathers had a younger brother, Major Thomas Augustus MOTION (14 IX 1866 - 20 II 1942) who was married on 12 July 1927 to (as her second husband) Lady Elizabeth HESKETH-PRICHARD, née GRIMSTON (21 VII 1985 - 13 IV 1975), daughter of the 3rd Earl of Verulam.
Major Thomas and Lady Elizabeth Motion had one child, Joan Elizabeth Mary MOTION (1929 - 12 XII 2015), who was married on 28 March 1953 to the Rt Hon Sir Murray STUART-SMITH, KCMG, PC (born 18 XI 1927). Their eldest child, Sir Jeremy Hugh STUART-SMITH, QC (born 18 I 1955), was married on 25 September 1982 to the Hon Arabella Clare MONTGOMERY (born 21 XI 1956), the only daughter of the 2nd Viscount Montgomery of Alamein.