Labour’s campaign to keep Britain in the EU has been lacklustre from the outset. Their leader’s heart isn’t in it, their Party is riven with factional infighting and they are plagued by fear of a possible repeat of the disaster in Scotland, losing the support of core voters who differ with them fundamentally on the issue. I wrote earlier in the week about the bizarre message they have settled on, which essentially involves attributing all of the Labour Party’s past achievements to Brussels and then telling voters Labour will never win another election.

But if the Opposition’s campaign was wheezing and sputtering to start with, now its wheels are coming off.

Gordon Brown has been touring the country this week, as though people are going to be won over by a former Prime Minister who is famous for calling working class voters concerned about immigration “bigoted”.

Angela Eagle struggled badly in last night’s debate using her Party’s flawed lines, and added a whole new one – claiming that “we have control of our borders” inside the EU, an assertion so patently untrue that it is only likely to further alienate traditional Labour voters who know they are being lied to. By contrast, Gisela Stuart, speaking for Leave, delivered a clear, measured and expert argument that “There is a successful union called United Kingdom and there is an unsuccessful union called the EU.”

Shortly after the debate, two Labour MPs – John Mann, on the right of the Party, and Dennis Skinner, very much on its left – announced their decision to campaign for a Leave vote, putting further wind in Vote Leave’s sails after a good fortnight. The news hasn’t been covered as extensively today as Sarah Wollaston’s defection was yesterday (in part because they weren’t previously declared for the pro-EU campaign) but it still matters.

Then this morning Andy Burnham launched an attack on the messages and tone of the Remain campaign, warning that: “We have definitely been far too much Hampstead and not enough Hull in recent times and we need to change that.” It isn’t the first time he’s posed as a sage from the North, but it’s an intriguing sign of growing worries on the pro-EU side of the debate.

We have known from the beginning that Labour supporters would make up a large proportion of swing voters in this referendum. Indeed, part of the challenge for Leavers is crafting messages and campaigns that can build a sufficiently broad coalition across those voters, Eurosceptic Tories, UKIPers and others. This week is the first time we have seen signs of real panic developing among Remainers that they are losing ground in the Labour column.

Privately, Labour MPs who started the campaign predicting an easy victory are now conceding that Leave may well be on track to win. With less than two weeks to go, and with Brown, Blair and Miliband already deployed along with every imaginable scare story, they are beginning to wonder what else they can do to reverse that situation.