A total of 307 Conservative MPs won seats at the 2010 general election*. The party came in 19 short of the 326 needed for an absolute majority in the House of Commons.
Had David Cameron decided to form a minority government and call a second election a few months later, this total might have gone up.
Instead the total has only gone in one direction: downwards.
It began this journey just a few days after the election, when Tory MP John Bercow was reelected as Speaker. This immediately reduced the number of Conservative MPs on the government benches to 306.
This number fell to 305 in November 2012, when Labour won the Corby by-election – a contest triggered by the decision of sitting Tory MP Louise Mensch to leave parliament.
It fell again in August 2014 to 304 when Douglas Carswell defected from the Conservatives to Ukip. This total was confirmed when Carswell held his seat of Clacton for Ukip in the by-election of early October.
Most recently it fell to 303 when Mark Reckless followed Carswell in swapping the Tories for Ukip. It will remain 303 if the latest opinion poll is correct and Reckless holds his seat of Rochester & Strood in the by-election of 20 November.
With the Liberal Democrats boasting 56 MPs**, the coalition government currently has a grand total of 359.
Might this number be about to fall further? There has been speculation that a convincing victory by Reckless in Rochester & Strood will prompt more defections to Ukip from the Conservatives. It should be said much of this speculation has been put about by Ukip itself, but it’s an outcome that ought to give the government concern. There is no danger of it losing its parliamentary majority before the general election (well, not unless 34 Tory MPs decide to leave the party). Any further defections, however, and the business of government would become increasingly difficult to manage. Votes would become tighter and scenes like the ones in the Commons on Monday would become more frequent.
An ever-dwindling Tory party would also add yet another entry to the list of narratives shaping the election campaign.
*Though not all were won on the same day of 6 May. The contest in Thirsk & Malton was postponed until 27 May because of the death of a candidate.
**Down one on the total number of MPs won at the 2010 election, due to Mike Hancock’s resignation in September 2014.