[6] He was sworn of the Privy Council in 1818[7] and served under the Duke of Wellington as First Commissioner of Woods and Forests between 1828 and 1830 and under Sir Robert Peel as Treasurer of the Navy and Vice-President of the Board of Trade between 1834 and 1835.

In 1841 he was summoned to the House of Lords through a writ of acceleration in his father's junior title of Baron Lowther and held office under Peel as Postmaster General between 1841 and 1845.

[1] Lord Lonsdale never married, but acknowledged three illegitimate children born to opera singers or dancers; he left them substantial sums in his will.

[1] On the day he died he waited in his carriage outside a London auction house, while an agent bid on his behalf on some lots of porcelain.

[15] A marble bust of him was sculpted by Edward Bowring Stephens, now in the National Trust collection at Hughenden Manor, Buckinghamshire.