Sarah Olney wins in Richmond Park with 22% swing to Lib Dems and five other by-election gains

This week's by-election results will be dominated by the news from Richmond Park, where the large number of doors the Lib Dems decided to call on today was a good straw in the wind about the likely result. You don't want to call on opponents and drive them out to vote by mistake, so how many doors you have to call on is a good sign of how many supporters, hoped for last minute tactical switchers etc. you have identified even though of course not every door ends up having behind it a supporter who goes to vote. Even so, that volume of doors knocked is the sort of volume that goes with winning unless your data is badly off.

Richmond Park result: Sarah Olney wins

Earlier in the evening, I wrote on Facebook about the Richmond Park by-election result:

• If reports of Richmond Park being neck and neck at weekend were true, then odds heavily in favour of Lib Dems winning, because when there's already been a big swing early in campaign to the party, it almost always continues, even accelerates in last days and that huge late volatility is normally greatly under-estimated by pundits (cf Brent in particular).

To put Sarah Olney's result in some context, it is worth remembering that in the 2015 general election, the Liberal Democrats lost the seat by 58% - 19%, and the opinion poll at the start of the campaign still had the party by 56% - 29%.

Since then, Sarah Olney and the Liberal Democrats have thoroughly out-campaigned the others

With, it seems, help from some unexpected places

Was that enough?

Yes:

Which also means, thankfully, that the Liberal Democrats will no longer have an all-male Parliamentary Party in the House of Commons.

The Labour vote share in Richmond Park - with a big drop on 2015 - is particularly significant because, as I wrote before:

• If the Liberal Democrats have regained the ability to squeeze Labour heavily in Conservative-Liberal Democrat contests, that is another important step on the road to Lib Dem recovery as such tactical voting (enhanced by bar charts, of course) is important to winning under first past the post.
• It will also be of wider political significance too, because it will show that voters are more willing to self-organise into an anti-Conservative coalition, without needing any formal party deals, pacts or memorandums.
• Such voter-led realignment has been the most effective form of realignment previously. Moreover, a big reduction in such tactical voting saw the Labour vote go up, helping the Conservatives win, in a string of formerly Liberal Democrat constituencies in the 2015 general election.

Other By-elections this week