British general election results for Parliament from 1802, the first election after the union between Great Britain and Ireland, right up to the 2019 election, which witnessed Boris Johnson’s Conservatives claim a comfortable majority (the best since 1987).

Prior to 1832, when the Great Reform Act extended the franchise and re-formed constituencies, the figures are only speculative estimations based upon the very sparse data available. They are therefore not definitive.

The gains or losses for each party generally reflect the changes relative to the number of seats they had going into an election, not the number of seats won at the previous election. Between 1802 and 1832, the lack of strong, consolidated parties permitted multiple factions, led by single leaders, to oppose or support different ministries between elections. Gauging the absolute figures of these factions or parties has proven difficult. More recently, by-elections and boundary changes would also have altered these figures. Therefore, the numbers represent solely the gain in seats compared to the parliament before each election.

In part because of constituency boundary changes, and other factors, the total number of seats and the size of the parliament has changed many times over the years. Today the total number of seats at Westminster is 650 (soon to be reduced subject to MP’s approval). Whereas in the past the number has at times been 500 – 550 or even lower. This means that changes in government and opposition parties seats are not always purely down to the general election results, but also boundary changes affecting the total number of seats up for election.

In this video, government seat bars are shown first, followed by the opposition, and then all subsequent parties. Parties share the same bar when they contest an election in coalition together.