Michel Barnier didn't just come to London to see Theresa May and David Davis. While in town, he also caught up with their Labour shadows, Jeremy Corbyn and Keir Starmer.

The EU chief negotiator's continued engagement with the Opposition is curious, given how touchy European leaders are about the prospect of British negotiators going around Monsieur Barnier's back to talk to them. "There will be no separate negotiations between individual Member States," the European Council decreed from the start of the process, insisting on the British Government directing its negotiating efforts "exclusively" towards the Frenchman. He, by contrast, can get away with talking openly with those aspiring to replace the Government.

What did Monsieur Barnier learn from Labour's frontbench? My colleague Peter Foster reports that the Labour leader went out of his way to woo him by showing how much easier he would be to negotiate with than the present Government. If he takes over, Mr Corbyn indicated - according to the EU - that he would unilaterally guarantee citizens' rights, be more receptive to oversight from the European Court of Justice, and be "open" to staying in the EU's Customs Union. Team Corbyn insist he had merely said that staying in "a" - not 'the' - customs union was "viable", but that would still leave the UK as a "silent partner" (as the CBI put it) in the EU's trade policy.