The Fixed Term Parliament Act (FTPA) was the love child of the Conservative – Liberal Democrat Coalition government.

It was designed primarily to ensure that a minority-coalition Government could – would – survive for a whole Parliament.

That was the primary aim and indeed that is what the FTPA achieves. It makes it very difficult to defeat an incumbent Government, even a minority one and especially a coalition (what a surprise).

Under FTPA there are two ways to force a Government out of office and trigger a new General Election.

The first is what enabled Theresa May to call GE2017. A motion supported by two-thirds of MPs can trigger an Election. Effectively this means only the existing Government can trigger an election this way, and then only with the support of the Opposition (which Labour provided this time).

The second is the Government loses a vote of confidence.

But under FTPA this is a very specific no confidence motion, the wording of which is laid down in the Act. Crucially anything else does not count, at least legally.

If such a motion is passed the Government then has 14 days to come up with changes (personal or policies) that would regain them a majority.

This gives the sitting government not one but two “get out of jail free” cards.

Firstly it means any defeat – for example on the Queen’s Speech or the Budget – does not amount to a “no confidence” vote and does not trigger an election or the 14 day process. The old conventions on this are dead.

This gives rebels licence to rebel against specific policies without bringing the Government crashing down.

Secondly, even with a FTPA defined “no confidence” motion rebels could vote against the Government the first time around and then, if they got the concessions they wanted (change of people of policy), vote to keep the Government in power at the end.

So its like a sort of pressure cooker with a built in pressure release system – that allows for rebellion whilst protecting, in practice, the Government. In modern terms its a sort of firewall around a minority, or coalition, Government.

The one thing the FTPA does not offer is an easy route for an Opposition to form a government without a General Election.

The only way that could happen is if the Government lost an FTPA “no confidence” motion and during the 14-day period the Opposition could come up with a plausible “ability to command a majority” in the House of Commons plan.

That is a massive hurdle as it would require a formalised Coalition agreement of some sort to be convincing.

Labour are currently saying they would just offer themselves – without any agreements – as an alternative Government. With their numbers, that doesn’t fly. They could (would) be voted down immediately. More importantly, they’d never get the opportunity as our (antiquated) constitutional arrangements means Corbyn would never get the call to go the Palace to ask for permission to form a Government.

They would need all the non-Tory MPs, including the DUP, to agree to be able to put forward a convincing case they could form a Government. That just isn’t credible, even if labour wanted to, which they don’t.

So in practice the FTPA protects the incumbent Government and allows rebels to blow off steam without triggering an election.

The Tories pledged to “repeal and replace” FTPA in their 2017 Manifesto. That is clearly not going to happen now.