In 1828 he was created Baron Cowley, of Wellesley in the County of Somerset, in the Peerage of the United Kingdom.

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.

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 9th Duke of Wellington.

The heir apparent is the present holder's son, Henry Arthur Peter Wellesley, Viscount Dangan (born 1991).