Marquess of Lansdowne is a title in the Peerage of Great Britain created in 1784, and held by the head of the Petty-Fitzmaurice family. The first Marquess served as Prime Minister of Great Britain. Wikipedia
Peerage: Peerage of Great Britain
Created by: George III
Creation date: 6 December 1784
First holder: William Petty Fitzmaurice, 2nd Earl of Shelburne
Heir apparent: Simon Petty-Fitzmaurice, Earl of Kerry
Motto: VIRTUTE NON VERBIS; (By courage, not words)