Evidence the UK has become more of a multiparty system

Decline in two-party vote share - Conservative + Labour vote share in 2024 = ~57% - Lowest since 1922 - 42% of voters chose parties outside the main two
More seats contested by multiple parties - Only ~48% of constituencies had Labour vs Conservative as top two - Down from 73% in 2019
Record number of third-party MPs - 117 non–Labour/Conservative MPs elected - Highest number since 1923
Growth of smaller and new parties - ~27% of votes went to parties outside the main 5 - Previous record was ~19.5% (2015)
‘Choice effect’ - Record ~4,400 candidates - Every constituency had at least 5 candidates - Greens and Reform UK stood in almost all constituencies
Fragmented voting outcomes - ~85% of MPs elected with less than 50% of the vote - ~41% elected with less than 40% - Shows votes spread across many parties

Reasons why the UK has not fully become a multiparty system

FPTP electoral system - Strongly favours Labour and Conservatives - Despite low vote share, they won ~82% of seats
Disproportionate seat outcomes - Reform UK: ~14% of votes → low % of seats - Greens: ~7% of votes → low % of seats - Smaller parties underrepresented
Continued dominance in Parliament - Commons still overwhelmingly controlled by two parties - Limits real governing power of smaller parties
System still delivers single-party government - FPTP maintains perception of stability - Reduces likelihood of coalitions despite voter fragmentation