A note on the methodology of this tool
Underpinning the functionality of this tool is a ranking system that places each seat on a priority scale of 1-650. This is predominantly informed by the size of the winner’s majority in 2017, but there is also a significant amount of artificial adjustment to account for local contexts. For instance, the seat of the new Speaker, Chorley, is our lowest-priority seat because convention dictates that he stands unopposed, and so there is no risk of a Tory winning. Likewise, any seats that have no Tory/DUP contention are pushed towards the bottom of the priority scale. Simply put, the higher the chances of unseating the incumbent Tory, or of a successful Tory challenge to a progressive incumbent, the higher the ranking of the seat. This then allows us to differentiate between seats to inform our users.
To make these comparisons even richer, we grouped seats into one of four categories - Key Marginal, Likely Marginal, Likely Safe and Safe. This then provides useful differentiation between seats and helps emphasise the importance of voting in some very key seats.
Where we have made a candidate recommendation in a seat, we provide this alongside our judgement of where a user’s vote is best placed between the two given constituencies. Elsewhere, we simply make a judgement of where their vote has more anti-Tory power.