How many members do the Conservatives have left? Unlike Labour, the Tories do not publish an official figure. But John Strafford of the Campaign for Conservative Democracy (a kind of Tory Jon Lansman) estimates that party membership is now a mere 70,000. That compares unfavourably to Labour's 570,000 (making it one of the largest parties in Europe) and to the Tories' 1997 level of 400,000.

The Conservatives' diminished membership was one of the reasons for their 2017 electoral humiliation. Labour's activists, battle-hardened from two leadership campaigns, easily outgunned the Tories in marginal seats.

But the Conservatives' micro-membership has other implications for their future. A party with just 70,000 dues-payers is ripe for entryism. Should some of the 2.4m people who voted Liberal Democrat or the 594,068 who voted Ukip (or the 16.1m who backed Remain and the 17.4m who backed Leave) sign up, they could shape the Tories' future.

The next Conservative leadership election will likely see British party members elect a new Prime Minister for the first time (Gordon Brown and Theresa May both secured the job unopposed). Though under current rules Tory MPs decide which two leadership candidates go forward to the membership, it is Conservative activists who have the final say. A swarm of liberal recruits, then, could elect Amber Rudd (or another Tory Remainer) as leader, while hard Brexiteers could do the same for Jacob Rees-Mogg (or another Tory Leaver). Indeed, Nick Clegg recently advocated the former strategy in his book How to Stop Brexit. (Alternatively, left-wingers could join to elect the most unpopular candidate.)

The Tories have traditionally sought to prevent entryism by imposing a freeze date before leadership contest, barring recent joiners from voting. But those who sign up now would likely be guaranteed a vote in the eventual contest to replace May. The Tories have long enjoyed mocking Labour's leadership rules (Toby Young, for instance, joined to vote for Jeremy Corbyn in 2015). But their subterranean membership levels now make them a takeover target.