Charles Watson-Wentworth , 2nd Marquess of Rockingham , KG , PC ( 13 May 1730-1 July 1782 ) was a British Whig statesman . He is most notable for his two terms as Prime Minister of Great Britain . Charles Watson-Wentworth , 2nd Marquess of Rockingham , KG , PC ( 13 May 1730 â `` 1 July 1782 ) , styled The Hon . Charles Watson-Wentworth before 1733 , Viscount Higham between 1733 and 1746 , Earl of Malton between 1746 and 1750 and The Earl Malton in 1750 , was a British Whig statesman , most notable for his two terms as Prime Minister of Great Britain .