Which conservative MP was known as Viscount Cranborne from 1903 to 1947 
South Dorset by-election, 1941:  The by-election was held due to the succession to the peerage by writ of acceleration of the incumbent Conservative MP, Robert Gascoyne-Cecil, as Marquess of Salisbury. Robert Gascoyne-Cecil, 5th Marquess of Salisbury: Robert Arthur James Gascoyne-Cecil, 5th Marquess of Salisbury, (27 August 1893 – 23 February 1972), known as Viscount Cranborne from 1903 to 1947, was a British Conservative politician.
Robert Gascoyne-Cecil