When historians combed the archives of one of Britain’s most famous postwar negotiations — the 1946 loan discussions with America — they happened upon the following poem:

In Washington Lord Halifax

Once whispered to Lord Keynes:

“It’s true they have the money bags

But we have all the brains.”

Led by John Maynard Keynes, the plucky Brits would leverage the old grey matter to run rings round their wealthy American counterparts.

Nothing could have been further from the truth. The loan discussions were an abject humiliation, consigning Britain to devaluation and an economic crisis. Far from outwitting the Americans, the British delegation was ill prepared and outmanoeuvred.

Yet the verse is a useful reminder: Brexit is not the first time we have entered crucial negotiations