Chesham and Amersham () is a parliamentary constituency in Buckinghamshire, South East England, represented in the House of Commons by Sarah Green, a Liberal Democrat elected at a 2021 by-election. History Contents and regional context The seat was created for the general election in February 1974. It comprises the southern part of the former Rural District of Amersham, including Amersham and the Chalfonts, previously part of the abolished constituency of South Buckinghamshire; and Chesham and the northern part of the former Rural District, transferred from Aylesbury. Political history and demography The local authority is in Buckinghamshire Council and the seat coincides with the abolished Chiltern District. It includes the towns of Chesham and Amersham and outlying villages within the Metropolitan Green Belt. The area is connected with Central London by the Metropolitan Line of the London Underground, as well as the London to Aylesbury Line and the Chiltern Main Line, both operated by Chiltern Railways. The constituency is also close to the M40 and M25 motorways. It is home to many affluent professionals. The two main towns are the only part of London Underground network amid an Area of Outstanding Natural Beauty (see Chiltern Hills as to which). Until the 2021 by-election was won by the Liberal Democrats candidate, the previous general election results in the seat since its creation had seen a Conservative winning margin of between 10,416 (Feb 1974) and 23,920 (2015) votes, in each case an absolute majority of the votes cast. In each of the general elections except two the Liberals, or subsequently Liberal Democrats, had come second, with results as high as 31.15 per cent of the votes cast. Labour came second only once, in 2017, when it achieved its best ever result of 20.6 per cent. UKIP came second in 2015, Labour in 2017 and the Liberal Democrats in 2019. Dame Cheryl Gillan MP died in office on 4 April 2021, and the seat was gained by the Liberal Democrats’ pro-EU Sarah Green in the subsequent by-election on 17 June 2021 with a majority of 8,028 votes. The Liberal Democrat win in the 2021 Chesham and Amersham by-election was seen as an upset in a historically safe Conservative seat, and party leader Sir Ed Davey tweeted that the result had "sent a shockwave through British politics". In June 2016, an estimated 55 per cent of adults voting in the EU referendum in the constituency