He went on to hold a number of other directorships, including Lloyds Bank (1928–38), Imperial Chemical Industries (1928–53), International Nickel (1928–59), and Shell Transport and Trading (1939).

David Lloyd George appointed him to the unpaid position of director of munitions in Scotland in July 1915, he joined the Air Board in December 1916 and was made a Knight Bachelor in February 1917.

[1] He didn't desire any further political power, and went on to serve on a number of government committees, including those on civil aviation, economies in the fighting services, and co-ordination between the navy, army, and air force.

(refer to The Scotsman newspaper, Saturday 03 November 1934) In 1935, he was a member defence policy and requirements committee and became advisor to Sir Philip Cunliffe-Lister, later Viscount Swinton upon his appointment as Secretary of State for Air.

In addition to his knighthoods, barony and viscountcy, Weir received an honorary doctorate from the University of Glasgow in 1919, the freedom of the City of London in 1957, the Order of the Crown of Italy, and he became a Commander of the Légion d'honneur.