Eton and Slough was a parliamentary constituency represented in the House of Commons of the Parliament of the United Kingdom. It elected one Member of Parliament (MP) by the first-past-the-post voting system.

The House of Commons (Redistribution of Seats) Act 1944 set up Boundaries Commissions to carry out periodic reviews of the distribution of parliamentary constituencies. It also authorised an initial review to subdivide abnormally large constituencies in time for the 1945 election.^[1] This was implemented by the Redistribution of Seats Order 1945 under which Buckinghamshire was allocated an additional seat. As a consequence, the new County Constituency of Eton and Slough was formed from the Wycombe constituency, comprising the Municipal Borough of Slough and the Urban and Rural Districts of Eton.

The constituency had some nationally known MPs: Fenner Brockway was a noted internationalist; Anthony Meyer, who later became MP for a constituency in Flintshire, Wales, challenged Prime Minister Margaret Thatcher as a "stalking horse" leadership candidate in 1989; and Joan Lestor, who later served as MP for Eccles, Greater Manchester, was a government minister and a founder of the anti-fascist newsletter Searchlight. The seat contained a prestigious public school (Eton College), yet had Labour MPs for most of its history, mostly because of the inclusion of the new town of Slough, which mainly voted for Labour. The sole occasion a Conservative MP won the seat, in 1964, it was represented by an Old Etonian, Anthony Meyer.