Charles Stewart Henry Vane-Tempest-Stewart, 7th Marquess of Londonderry KG MVO PC PC (Ire) (13 May 1878 – 10 February 1949), styled Lord Stewart until 1884 and Viscount Castlereagh between 1884 and 1915, was a British peer known for his political career in Britain.
He is best remembered for his tenure as Secretary of State for Air in the 1930s and for his praise of Nazi Germany in the 1930s. He was forced out of the government in 1935 and never returned.
His main record at the Air Ministry included:
- He preserved the core of the RAF at a time when even this was under threat from the Treasury. He encouraged the planning of vital new fighter aircraft such as the Hurricane and Spitfire. It was under his tutelage that radar was developed for use by the RAF. The Staff College at Cranwell was opened in the last months of his time as air minister....[But in underestimating the Luftwaffe he was] badly astray over the issue of German air strength in 1934–5."