After almost 48 hours of scratching my head, I've finally managed to convince myself that the BBC are indeed counting John Bercow as a Tory in their summary of the election results. What confused me is that there's one unspecified 'other' MP listed, which I thought might be the Speaker, but of course I should have realised it's the independent Sylvia Hermon. So that's good news - it means the de facto government majority (excluding Sinn Féin) is 16 rather than 18.
We've been adjusting to the idea of the SNP having a huge moral mandate but without holding the balance of power, but in fact the arithmetic is tight enough that there must be at least a 50/50 chance that the Tory majority will be wiped out well before the next election. As even the SNP have discovered at Holyrood, government majorities invariably tend to go down rather than up. Every by-election defeat, defection or expulsion reduces the majority by 2, so it would take only 8 such events to return us to a hung parliament. Even after about 6 or so, the arithmetic moves so close to a tie that the concept of majority government ceases to be particularly meaningful - in days gone by, a tiny majority of 5 or less wasn't even considered to be a "working majority".
Historically, what governments without a comfortable majority generally do is look for a favourable moment to call a snap election, after two, three or four years. Until Thursday, we assumed that option was no longer on the table because of the Fixed Term Parliaments Act. Although the legislation could be repealed by simple majority vote, the theory was that the opposition parties would prevent that happening, because it would never be in their interests to allow the Prime Minister to choose the date of the next election. But due to the unexpected Tory majority, the opposition parties currently don't have a veto. Will Cameron take the opportunity while it's there?