Although the Labour Party has existed for over a century, only once have we actually come from opposition to win a convincing parliamentary majority.
No, it was not in 1945, when Labour had been part of the wartime coalition government for 5 years already.
The only time we have won a convincing mandate from opposition was in 1997.
In order to secure that victory, we had to win over the press and many powerful corporate allies, by promising to implement a programme which would never fundamentally challenge their interests.
And so once in government, we did just that.
Yes, it’s great that we introduced the minimum wage, Sure Start and built new schools. But we did it largely through PFI deals that handed power and profit to the private sector where once we had enjoyed universal public services.
In the meantime we let the inequality gap grow while the industrial regions rusted, because anything else would have been too expensive, and would have challenged the agenda of the City.
Now we can see where that has led: Brexit, and a 20-point poll lead for the Tories.
Let’s be clear what that means today. We have lost Scotland. The Tories are dominant and UKIP or a successor organisation pins us back in a swathe of seats.
The boundary review is going to deprive Labour of another 40 seats. There is simply no hope of a parliamentary majority for Labour under these circumstances.
Those of us advocating a progressive alliance strategy for Labour are responding to this stark reality.
The initial proposition of the progressive alliance strategy is simple.
There are literally dozens of Tory-held parliamentary seats wherein the combined vote for Labour, Green, Liberal Democrat and Plaid is significantly larger than the Conservative vote.
There are many key target seats for Labour where the Lib Dem/Green/Plaid vote is significantly higher than the Tory majority.
There are also many constituencies where Labour has no hope of ever taking the seat.
In many of those, the Labour vote is higher than the Tory majority over one of those other parties.
Under these circumstances, it makes sense to try to work towards local agreements which would see Labour and other parties of the left and centre stand down in each other’s favour.
This would only be in situations where those standing down have no hope of winning. It would only be in places where local party members supported the idea.
The most common objection to this proposal is that it would mean co-operating with the Liberal Democrats, who are “are not progressive” or are “no different from the Tories”.
These kind of claims simply miss the point. The issue is not whether the Liberal Democrats are cool enough to be our best friends. The question is only whether we can work with them to beat the Tories.
The Liberal Democrats are what they are. They are not conservatives or socialists but centrist liberals, mild social democrats and social-liberals.
The Liberal party and the Liberal Democrats formed coalitions with the Tories in the 1930s and the 2010s, but they also supported minority Labour governments in the 1920s and the 1970s.
Indeed, the Labour Party only came into existence as an effective force in British electoral politics as a result of the anti-conservative alliance and pact of 1906, which saw Labour and Liberal candidates stand down in each other’s favour in key seats.
So what we are proposing is nothing new, but in fact the most normal way for Labour to achieve progressive goals.
An objection which one often hears to the idea of a progressive alliance is that doing deals with Liberals or even Greens amounts to “crossing class lines”.
Even in strict Marxian terms, this is daft.
The Labour Party is hardly a pure workers party, but includes significant elements which are closely tied to key sections of capital (finance, defence, energy etc).
By contrast, the Liberal Democrats and Greens do not represent or have the backing of any significant section of the capitalist class, having their main social base among well-paid professionals and the more socially liberal and egalitarian sections of the commercial middle classes.
In strictly Marxian terms, it must be clear that the British working class is currently too weak, disorganised and demoralised to have any hope of mobilising autonomously against its enemies for the foreseeable future.
Without some form of coalition with the more progressive sections of the middle classes at least, there is no hope of defending what remains of the social democratic settlement or challenging the right’s desire to turn Britain into the world’s biggest offshore tax haven.
Supporters of the progressive alliance idea want Labour to retain a clear identity as the party of organised labour and the public sector.
But we are also realistic about the fact that in Britain in 2017, a party with a strong radical identity has no hope of winning an election without co-operating with other potentially sympathetic parties.
Our aim is not to drag Labour to the right, but to allow it to lead a progressive coalition from the left.
In fact this has almost always been the only way that Labour has been able to operate as a successful, reforming electoral force.
The sooner we remember that fact, the better.
Jeremy Gilbert is Professor of Cultural and Political Theory at the University of East London and a member of the Compass Management Committee. @jemgilbert
The Progressive Alliance: Why Labour need it can be viewed here.