Sir John succeeded his father, Col. Sir Edward Archibald Ruggles-Brise, 1st Bt., in 1942. He was educated at Eton and served in WWII, received a Territorial Decoration, became an Officer of the Order of the British Empire, and was named a Commander of the Order of the Bath (1958). He served as a Deputy Lieutenant and Justice of the Peace for Essex in 1945 and 1946, respectively, Vice-Lieutenant from 1947, and Lord Lieutenant from 1958. From 1958-66, Ruggles-Brise was President of the Essex T. and A. Force Association [Territorial and Air Force?]. His other activities included those of Church Commissioner from 1959-64, President of the Country Landowner's Association in 1957 and 1958, Chairman of the Standing Council of the Baronetage from 1958-63, Pro-Chancellor of Essex University from 1964, and honorary Freeman of Chelmsford.