September 27, 2023 - 3:30pm

When the Conservatives won the Uxbridge and South Ruislip by-election, there was a temptation to get carried away by the result.

Squeaking home by a handful of votes obviously had an outsize and useful effect on how the three by-elections were reported, but a result so heavily shaped by local factors cast only very limited light on the national picture.

Yet it seems the capital might be about to give Rishi Sunak another fillip: recent polling says the Tories are only three points behind Labour in the race for the London mayoralty.

Now, one swallow does not a summer make. Yet allowing that the odds still favour Sadiq Khan, the fact that a win for Susan Hall in May is apparently so plausible is remarkable, especially when the Tories are so far behind in the national polls.

London leans liberal, if not always in its social attitudes then reliably in its voting patterns. That Boris Johnson was able to twice win City Hall was taken as testament to his ability to reach out beyond traditional Conservative voters; there was and remains concern in the party that he would prove an historic exception.

At Westminster, meanwhile, the Tories’ position in the capital is decaying. Seats which David Cameron either won or came close to winning in 2010 now have five-figure Labour majorities; veteran MPs such as Theresa Villiers and Iain Duncan Smith won only narrowly in 2019, during a national landslide, and are surely doomed.

Hall, who launched her campaign beneath a replica Spitfire and has been dogged by revelations about her injudicious tweeting, is no Johnson. So what could her pathway to victory be?

It can be narrower than his, for starters. Earlier this year the Government switched the voting system to first-past-the-post, which means no second-round runoff where Left-leaning voters who backed the Liberal Democrats or Greens can switch.

Should significant numbers of them stick with their first preference, that will hurt Khan, likely much more than Reform UK (whose vote has never yet lived up to its polling) hurts Hall.

But the critical factor may be that the mayor’s policies, most obviously the expansion of the Ultra-Low Emission Zone, could have been precisely calibrated to energise voters in outer London, where the bulk of the Conservative vote lives (and drives).

If the campaign comes down to who can better mobilise their base, that could very well tip the balance.

Whether that represents a long-term future for the Tories in London is less obvious. Outer London is no more immune to change than the Blue Wall, and equally vulnerable to being settled by angry, Left-leaning voters priced out of the city proper by spiralling rents and property prices.

There are urban cohorts, such as the “Cautiously Hopeful Strugglers” identified by YouGov, still prepared to give the Conservatives a hearing. But that opportunity will be squandered if the party doesn’t bother to develop a policy offer for them, and settles for eking out another historically-exceptional win from its comfort zone.

Henry Hill is Deputy Editor of ConservativeHome.