This book assesses the importance of nine UK parliamentary by-elections from 1919 to 2015 and their impact on the progress of nationalism within the four nations of the United Kingdom. Contributors include the leader of the Scottish Liberal Democrats (Willie Rennie MSP) who writes about his experience as a candidate in the Dunfermline and West Fife by-election. Rory Tinman writes about the Fermanagh and South Tyrone by-election in 1981 which is based on recent interviews with participants on the Irish Republican side of the debate. The election was won by H-block prisoner Bobby Sands who died just a few weeks after the election whilst on hunger strike. Other contributors include Daniel Burrill (Lincoln, 1973), Ryan Davies (Newport, 1922), Miles Fowler (Carmarthen, 1966), Ben Manley (Mitcham and Morden, 1982), Camelia Manzoori (Plymouth Sutton, 1919), Iain Miller (Northern Ireland, 1986) and Tom Wowk (Kilmarnock, 1933). As the book focuses on twentieth century by-elections there are a number of examples of seats which were significant in the progress of Irish, Welsh and Scottish nationalism. However, with the examples of Lincoln and Mitcham and Morden these show the impacts of Europeanisation and the UK's membership of the EEC and the impact of British nationalism, in response to the Falklands War.