How tactical voting might affect the British election

That is because of a big rise in the number of centre-left crossover voters who are prepared to cast their ballots for more than one party (see chart). This increases the chances that people will opt for a party other than their first choice in order to defeat the Tory candidate in their constituency. In 2019 around 17% of all voters were considering both Labour and the Liberal Democrats, compared with only around 13% in 2015. In May 2023 it was almost 22%.