That position is a marked difference to the Government’s view, repeated by the Prime Minister’s Official Spokesman this morning: “The Government will not be joining a customs union. We want to have the freedom to sign our own trade deals and to reach out into the world.”
Yet with Theresa May only having a Commons majority thanks to the support of the DUP, it would not take many rebel Tories backing Labour to force the Government to keep the UK in a customs union.
Here’s how Corbyn’s speech may have set off a chain of events which could see May out of office, and Labour in Government.
First up, we need to understand the maths involved. Thanks to the support of the DUP, the Tories have 326 MPs who it can instruct to march through the voting lobbies in support of its policies.
The opposition benches have 313 MPs.
In order to win a vote, the Government needs to get the support of 320 MPs.
However, nine Labour MPs backed Brexit in the referendum, and so would be minded to support the Tories’ stance:
We can take one of those off straight away as Labour’s John Mann said he welcomed Corbyn’s speech.
Roger Godsiff and John Cryer both followed party orders and voted against the Repeal Bill in September, showing they are willing to put giving the Government a bloody nose above their eurosceptism.
So there are now effectively six Labour Brexiteers.
That means there are 307 MPs on the opposition benches who would support keeping the UK in a customs union.
Labour therefore needs to tempt 13 from the Government side to back its plan.
WHO COULD DEFECT?
Amendments tabled to the Trade Bill to keep the UK in a post-Brexit customs union have 11 Conservative signatories at present:
That leaves the pro-customs union side on 318.
That list doesn’t include pro-EU MPs such as Chelmsford’s Vicky Ford and East Renfrewshire’s Paul Masterton. If they joined the 11 already signed up, it would give the pro-customs union side a majority, and lead to a Government defeat.
HERE’S THE TRICKY BIT…
If it looked like a Government defeat was on the cards, would those Labour Brexiteers still vote with the Tories? Left-wing veteran Dennis Skinner would no doubt have a lot to answer to if his vote was the one which spared the Tories’ blushes.
The flipside to that is how many Tories who threaten to rebel would actually go through with voting against their party on such a key issue?
Ken Clarke, Anna Soubry and Nicky Morgan may well have the guts to defy party whips, but some of the newer MPs – Vicky Ford, Paul Masterton – may not.
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DOES DEFEAT MEAN AN EARLY ELECTION?
Not necessarily. The Fixed Term Parliaments act means that Government being defeated on legislation – even on such a vital piece as this – will not trigger a general election.
However, an early election could be called if a vote of no confidence in the Government is passed, or if two-thirds of MPs back dissolving parliament and going to the country.
Theresa May could decide that defeating the customs union amendment is so vital to her Brexit negotiations, she frames it as a virtual no confidence vote.
The message to Tory MPs would be: “Defeat me on this, and I’ll have to call an early General Election – which Labour might win.”
Would Brexiteers MPs support the calling of an election, fearing the UK’s entire negotiating strategy had been undermined by Parliament? Potentially, but the election would have to truly be a snap vote in order to get back to talks in Brussels before the Article 50 process runs out.
Would pro-EU Tory MPs really risk putting Corbyn in Downing Street? Some would take that gamble in order to get the deal they want on Brexit.
It may be that making it a do-or-die vote is the best way for May to survive.
Theresa May might decide pushing it to a vote is all too risky. With the margins of error so close, it might be simpler to seek a compromise with the rebels. It could be the Government puts forward its own amendment promising to keep customs union membership on the table if a certain set of conditions can be met.
Yet while this action might appease the pro-EU wing of her party, it will infuriate the Brexiteers.
Last week, 62 Tory MPs wrote to May calling for her to take a harder line with the EU in the negotiations. Promising to look again at customs union membership would only rile them up further. Just 48 Tory MPs need to call for a leadership contest for May to find herself out of office.
The resulting leadership vote could lead to a Brexit hardliner, such as Jacob Rees-Mogg, take over as Prime Minister. If that happens, there could be further splits as pro-EU MPs such as Anna Soubry walk out of the party, depriving the Government of its majority and triggering another election.
Which could lead to...
Prime Minister Corbyn.