Plurality, or First Past the Post is the current electoral model of the United Kingdom. It is also used by America, Belarus, and Canada
This polling rate, while reported on the national level, will only effect constituencies where these parties chose to run. It's important to note that this is polling rates before any changes made to the voting system. Keep this in mind when picking your rates, as otherwise this can lead to surprising results!
Individual Constituencies represent the current system
Plurality gives each voter a single vote, seats are given to the candidate/party who receives the biggest vote. In a multimember constituency, these are awarded as proportionally as possible.
For 'No Change', this slider is ignored.
Under a system which feels proportional to a voter, this proportion will have votes from the top two parties in a constituency group be reallocated.