Sir William Lowther, 1st Baronet, of Little Preston and Swillington, and his wife Anne Zouch.

His younger brother was Sir John Lowther, 1st Baronet, who also married a daughter of the 9th Earl of Westmorland.

[3] Lowther was briefly Member of Parliament for Appleby in 1780, for Carlisle from 1780 to 1784 and for Cumberland from 1784 to 1790.

A Tory in politics, he seems to have been tolerant and well-liked, disdaining sabbatarianism[4] and serving as patron for a number of painters and authors, including William Wordsworth.

[5] On 12 July 1781, Lord Lonsdale was married to Lady Augusta Fane (died 1838), the eldest daughter of John Fane, 9th Earl of Westmorland and, his first wife, Augusta Bertie (eldest daughter and co-heiress of Lord Montagu Bertie, fourth son, by his second wife, of Robert Bertie, 1st Duke of Ancaster and Kesteven).