Yesterday’s defeat in the Lords over the UK Internal Market Bill places the Government in a tricky position. Unless the stand-off is resolved, it risks undermining Britain’s negotiating position just as talks with the European Union enter the final straight. From the FT:

“Peers voted by 433 to 165 on Monday night to remove clauses in the internal market bill that would allow ministers to overrule parts of the EU withdrawal agreement. It was one of the heaviest government defeats in the upper house in recent years.”

The battle over the Irish Protocol is especially significant, coming as it does when the full consequences of the ‘more practical’ decision to impose an Irish Sea border are becoming clear. This week, the First Minister and Deputy First Minister wrote a joint letter to the EU urging it not to impose checks which threaten food supplies in the Province.

(A concerted effort to pin the blame for this on those who insisted on a sea border over a land border, despite the much higher value and volume of commerce between Northern Ireland and the mainland versus either the Republic or the EU, is conspicuously absent.)

For his part, Boris Johnson insists that he will press ahead with the Bill. He already compromised on the Bill to get it through the Commons. But what’s his way forward?

If it were less urgent, the Government could fall back on the Parliament Act and simply force the Bill through in the next session. But the provisions set out in the UKIM Bill need to be in place by the end of the transition period, which doesn’t leave enough time for this. Without the power of compulsion, the Prime Minister can only send the Bill back to the Lords again (in the process known as ‘ping pong’) and hope they back down.

Will they? Some of Johnson’s supporters are quite bullish. They feel that if the Lords is seen to be undermining the negotiations at this crucial stage – in concert with Joe Biden, no less – they will put themselves on the wrong side of public opinion and run the danger of encouraging the Government to bump some form of Lords reform up its constitutional agenda. They point out that this was how an earlier stand-off with the Upper House over Article 50 ended up playing out.

Others suspect that what is more likely to happen is that Johnson will conclude a deal which renders the most controversial parts of the BIll unnecessary, and then drop them.

A middle course might be simply to wait until we know one way or another if there’s going to be a deal. If there isn’t, then in theory the Prime Minister could try to strongarm the Lords into accepting the Bill because it would be essential to have a new legal structure in place for the UK internal market before January. Johnson could also claim – although his opponents would obviously not agree – that the EU’s refusal to move on this point justified the Government’s initial concerns.

One thread running through all of this is that so many of the Government’s problems are self-inflicted. Even its more bullish supporters were furious that Brandon Lewis had (in their view falsely) conceded to its opponents the crucial idea that the UKIM proposals are in breach of international law. Meanwhile that the Government is still facing such sustained opposition from people praying in aid of the Belfast Agreement highlights once again the steep price London has paid throughout the Brexit process for not developing its own understanding of what that text actually commits it to.