Jeremy Corbyn tried a new approach yesterday: he launched a policy. Perhaps he thought it might shift a few more votes than rowing about anti-Semitism, or waging war with his deputy on the future of their party, or voting with the Conservative Government on Brexit.

But despite his education launch, the Labour leader seems to have missed one crucial lesson: that what he now says on policy no longer matters. Even if he comes up with a policy (albeit in this case, one borrowed from the Lib Dems), nobody is listening. Because he no longer has any credibility on the central currents in British politics, what he says on the underfunding of schools or hospitals is just ignored – beyond, perhaps, a Momentum echo chamber.

Because Labour is extreme, divided and without economic credibility, nothing it says can have any bearing. No one, least of all the Labour leader, seriously expects Jeremy Corbyn to reach Number 10.

For a progressive, these are bleak times: we might have the most disastrous, self-harming Government many of us have experienced, but May glides on. And this despite the Tories’ Brexit plans unravelling a little more each day – her admittance while grubbing for a trade deal in Saudi Arabia yesterday that she will not reduce immigration in the immediate aftermath of leaving the EU is just her latest U-turn.

Corbyn accuses 'failing' media of being 'obsessed' with his leadership

So the leaked report by her pollster Lynton Crosby is intriguing. In it, Crosby warned May against an early general election. But not because of fear of Labour. No, the “Official Opposition” could be brushed aside. He said he feared the Liberal Democrats, who he said were on course to win back virtually all seats they lost in 2015.

I make no such boasts. We were thumped in that election, and it is a long road back. But with Sarah Olney’s win in Richmond Park, over 30 council gains across the country, and the near doubling of our membership since the election, everything points to a Liberal Democrat resurgence. Adam Boulton is one of many commentators to note that for all the media intoxication with Ukip, the Liberal Democrats are now firmly back as the undisputed third force in British politics.

But I am more ambitious than that. General elections are not an each-way bet. Coming third is not enough. Politics is moving at an extraordinary pace. Labour’s mess looks so terminal, and Tory mismanagement so shocking, that there is no limit to our opportunities.

48 per cent of people voted Remain in the most important question to face the country for a generation, yet there is just one Remain party, the Liberal Democrats, ranged against the three Brexit parties – Ukip, Conservatives and Labour. Labour, to its lasting shame, traipsed through the lobbies in support of May’s hard Brexit.

Add to that 48 per cent a sizeable chunk in the 52 per cent who thought they were voting for a soft Brexit, remaining in the world’s largest market, and the political space for the Liberal Democrats is vast.

Even Labour does not seriously think it will win the 50 seats held by the SNP in Scotland, while in England and Wales Labour is, if anything, falling back from what now looks like the high-water mark of support under Ed Miliband. And this in the mid-term of a disastrous Conservative Brexit government, with the public starting to feel a Brexit squeeze caused by a falling pound and rising prices, and jobs shipping to the Continent.

Brexit: Theresa May on trade, security and the single market

So if there is be a break in the political weather any time soon, the sun will have to shine on the Liberal Democrats. This is evident in the Gorton by-election, where once they had to weigh the Labour vote. Now, when you explain that Labour voted for Brexit despite every one of their amendments being rejected, life-long Labour supporters are saying they can never vote for Corbyn’s party again. In trying to ride two horses, Brexit and Remain, the Labour leader finds himself falling headfirst into the first Brexit fence.

My party doesn’t always receive the fairest of press, but journalists have been tweeting how the Liberal Democrat press operation knocks Labour’s into a cocked hat. That is partly down to professionalism, but it is mainly down to us, unlike Labour, having a clear message: opposing a divisive, hard Brexit and working to build a successful economy trading with our European friends to give the NHS and schools the long-term funding they need.

Those many liberals in the Labour Party now have a choice: are they going to let this disastrous Conservative government wreck the lives of a generation of British workers by recklessly losing them their jobs, taking away their rights, and raising their cost of living? Or will they work with the only party up for the fight, the Liberal Democrats?