Arms: Quarterly: 1st & 4th, Gules, a Cross Argent, in each quarter five Plates saltirewise (Wellesley); 2nd & 3rd, Or, a Lion rampant Gules, ducally gorged Gold (Cowley); over all at fess point an Annulet for difference. Crest: Out of a Ducal Coronet Or, a Demi-Lion rampant Gules, holding a Staff erect proper, and therefrom flowing to the sinister, a forked Pennon, from the Staff two thirds per pale Argent and Gules, charged with a Cross Gules. Supporters: On either side a Lion Gules, ducally gorged and chained reflexed over the back Or, charged on the shoulder with an Annulet for difference.
The first Earl was succeeded by his eldest son, the second Earl. He was a Lieutenant-Colonel in the Coldstream Guards and fought in the Crimean War. His great-great-grandson (the titles having descended from father to son), the sixth Earl, served as a Lord-in-waiting (government whip in the House of Lords) from January to March 1974 in the Conservative government of Edward Heath. He was succeeded in 1975 by his uncle, the seventh Earl, who was the eldest son from the second marriage of the fourth Earl and the half-brother of the fifth Earl. As of 2017[update] the titles are held by the latter's son, the eighth Earl, who succeeded in 2016. As a male-line descendant of the first Earl of Mornington, he is also in remainder to this peerage and its subsidiary titles, which are now held by his kinsman the Duke of Wellington.