Conservative vote share in the Welsh Assembly can be almost perfectly predicted based on Westminster vote share. The correlation is a mighty .97 with the closest thing to an outlier being Kirsty Williams’ heroics in Brecon.

As for change in vote share, no key Conservative seats appear to be outliers from a fairly healthy correlation of .55. Pontypridd stands out because of an enormous improvement in Conservative share of the vote in 2015, which was from a deposit-losingly low base.  Cardiff Central stands out as a relatively good result in the Assembly, perhaps because their vote was squeezed in 2015 – the seat was a high profile Labour-Lib Dem battleground.

The numbers bear out the perception that the Conservatives had a bad Assembly election – they got a mean of 20.2% of the vote, as opposed to 26.2% in 2015. Their direction of travel was also worse – a mean reduction of 3.8 percentage points as opposed to a gain of 1.3%. So the distribution of conservative votes across the country is extremely predictable based on Westminster results, but the overall level was a disappointment for them.