It’s come a day earlier than I expected, but we are now entering the 'government of national unity' phase of the Brexit debacle.

Nicky Morgan, once a Tory Cabinet minister, said this on the Today programme:

'It may well be that if you end up with a cross-party approach to finding a majority in the House of Commons, it might be that you need a cross-party approach to implementing it.

There have been periods in our history when we have had national unity governments or a coalition for a very specific issue.'

Tom Watson of Labour has made similar noises.

The logic is sound enough: there is almost certainly a majority in the Commons next week to pass Theresa May’s Withdrawal Agreement in its current form, attached to a Political Declaration that more explicitly commits the UK to seek membership of a customs union with the EU in its future relationship.

But this majority is made up of quite a lot of Labour MPs, quite a lot of Tories, and possibly even the SNP.

Passing a deal in that way would end the current Brexit impasse, but might well break the Conservative Party, many of whose MPs would rather we leave without a deal than sacrifice the potential benefits that arise from spending a decade negotiating trade deals with the US, China and India - only to discover that in trade negotiations, the bigger party calls the shots. But then, maybe the party is already broken: a Conservative Party that has no use for Dominic Grieve as an MP is neither Conservative nor a party. It has become a revolutionary sect.

The loss of scores of ministers and the visceral rage of the Brexiteers would cripple Theresa May’s already feeble ministry and very likely lead to a new confidence vote. Would passing a Customs Union deal next week lead to a rapid general election?

Not necessarily: the same majority for the deal might also save the government from collapse in a confidence vote.

But what if May does oversee the vote for a WA+CU, then her angry Brexiteer colleagues do vote with Jeremy Corbyn to bring down her government?

Here the Fixed Term Parliaments Act comes into play. It says that if the May government falls, there is a 14 day period in which an alternative government can be formed.

Which is the sort of scenario that Morgan and Watson are thinking of. Of course, forming a whole new unity Government that could command the confidence of the Commons in that 14 day period would require all sorts of extraordinary things: a level of cross-party cooperation that has so far proved impossible; agreement on who should serve as PM and in Cabinet; and finally, the agreement of the monarch.

Now, I have no inside knowledge here: all I know of the possibility of a national unity government I gleaned from political and civil service friends; I have no royal sources. But I would be very, very surprised if the only people pondering this scenario today are MPs and journalists.

Such a national government would be an extraordinary thing, and probably relatively short-lived: it might hold office only long enough to ratify the WA before giving way to an autumn general election where what remained of the main parties stood on their offer of how to negotiate the future relationship. The rump Tories presumably would promise to rip up the PD and seek either Canada or the deep blue sea.

Those Tories who had backed the national government, meanwhile, would need a new political home. Their prospects might be bleak.

Of course, extraordinary events have extraordinary effects. Remember 2010 when the coalition was formed: political consensus said it was an aberration, that it could not last and voters would bring it down quickly. In fact, the electorate welcomed sensible cooperation at a time of national need; the Coalition lasted five years. More than once during the Coalition years, some senior Tories pondered turning a one-off governing partnership into a lasting change in the party system.

In our last moment of national crisis, a huge fiscal challenge, politicians put party politics aside to govern together, and voters liked it. Today’s national crisis is a political and governmental challenge. There are still a lot of possible outcomes to the current mess, but many of them are much worse than a government of national unity.