BORIS JOHNSON put on a bravura performance yesterday, with a speech full of great lines and amusing thoughts – it will be difficult to look again at Speaker John Bercow and not think of him eating a kangaroo testicle.

Then details of Mr Johnson’s new plan to resolve the Irish border question landed.

It is hard to know whether Mr Johnson is having a joke with the EU, the Irish and the DUP, or whether he is serious.

He admits there will have to be some forms of physical checks – all those promises about magical new technology have vanished – so there will be a border between the two parts of the island, with all the dangers that that entails.

And Northern Ireland more or less stays in the single market and so will have a different regime from the rest of the UK, necessitating another border in the Irish Sea – so much for strengthening the union.

Yet we welcome the proposals. At long last, Mr Johnson has put something forward, and now he must enter negotiations seriously.

This cannot just be another of his wizard wheezes, putting forward a flawed plan that he knows the EU will reject and then blaming the 27 for its failure.

As Mr Johnson says in his letter, if we don’t get a deal, it will be “a failure of statecraft”. And it will be his failure – a failure of negotiation caused by him deliberately creating an artificial do-or-die departure date.

So follow this letter up, Boris. Don’t joke around. We need a serious deal.