When his older brother, George Henry, died at the age of 10 from measles, Walter became heir apparent to the Dukedoms of Buccleuch and Queensberry.

[6] Buccleuch set out his ideas of the duties of a great landowner in a speech given at Branxholme Fete in 1839: What has been entrusted to me has not been given that it might be wasted in idle or frivolous amusements; nor would I be justified in wasting the hard earnings of the tillers of the soil by carrying them away and spending them in foreign countries, but I wish to see them employed as the means of producing good to them and to the country at large.

[6] A great Scottish land magnate, Buccleuch was a Conservative in politics, and was appointed a Knight of the Garter in 1835 and a Privy Counsellor in 1842.

Isabella Elizabeth Byng, daughter of the 4th Viscount Torrington, on 13 August 1829 at St George's church, Hanover Square, London.

He was buried in the family crypt of the Buccleuch Memorial Chapel in St. Mary's Episcopal Church, Dalkeith, Midlothian.