Hon. Oscar Montague Guest (24 August 1888 – 8 May 1958) was a politician in the United Kingdom, initially with the Liberal Party and later as a Conservative. He was twice elected as a Member of Parliament (MP).
He was the youngest of the nine children of Ivor Bertie Guest, 1st Baron Wimborne (1835–1914) and his wife Lady Cornelia Henrietta Maria Spencer-Churchill (1847–1927), daughter of John Spencer-Churchill, 7th Duke of Marlborough, aunt of Sir Winston Churchill. The Guest family were wealthy industrialists whose interests included the fastenings-manufacturing company Guest, Keen and Nettlefolds (now known as GKN). Three of Oscar's brothers (Henry, Ivor and Freddie) were also MPs, as had been their grandfather John.
Political career 
He did not stand for Parliament again until the 1935 general election, when he was elected as Conservative MP for the Camberwell North West constituency in South London. At the 1945 general election, he did not contest the Camberwell seat (which was won by the Labour Party candidate), but stood instead in the Breconshire and Radnorshire constituency in South Wales, where his nephew Ivor had been MP in the 1930s. Oscar was defeated there, ironically by a much wider margin than the Labour majority in Camberwell North West.
- Historical list of MPs: L (at Leigh Rayment's Peerage pages)
- Historical list of MPs: C (at Leigh Rayment's Peerage pages)
- Hansard 1803–2005: contributions in Parliament by Oscar Guest
|Parliament of the United Kingdom|
Sir Maurice Levy
|Member of Parliament for Loughborough
|Member of Parliament for Camberwell North West