After a day of meetings with EU officials, Philip Hammond was upbeat as he sat in the opulent mirrored garden room of Britain's embassy in Brussels. It was mid-September, and he said the migration crisis tearing through Europe had focused the minds of leaders on Britain's own problem with immigration. Once the forthcoming Polish elections, which were expected to unseat the difficult left-wing government, were over he foresaw a "flurry of activity" to address the UK's demands.

"When I've had a few glasses of champagne, I think there might be agreement at the December European Council, a package and we can move forward," the Foreign Secretary disclosed, adding that when he wakes with a hangover, things look a little worse.

Other government figures said the referendum, if all went smoothly, could even be as soon as April.

But this week David Cameron was forced to admit such optimism was misplaced. A do-or-die attempt to force Europe to accept a deal before Christmas by threatening to lead the campaign to leave if he did not get his demands has unravelled. He now accepts there will be no deal before February - and the prospect of Brexit appears closer than ever.