Long before the official start of the EU referendum campaign, I paid a visit to the newly opened office of the Vote Leave campaign. The smartly dressed young men and women looked like the sort of volunteers one might expect to see at a Conservative party campaign office. But the huge Vote Leave logo across the wall was in exactly the same shade of red associated with Labour election posters. When I pointed this out, one of the volunteers smiled: “That’s not a coincidence.”

Well, of course it isn’t. And it might help explain why, according to recent research, only about half of traditional Labour voters realise their party’s policy is to back the campaign led by David Cameron to keep the UK in the