There is a destructive mindset in the Labour Party that says that by forming a coalition with the Conservatives the Lib Dems are acting true to form, with the implication that there has never been a 'progressive consensus' - merely This Great Movement Of Ours and Them. But let's look at Labour's relations with the Conservatives.
Labour's way of preventing a Conservative government over the past decade has been to turn itself into one. The concessions the Lib Dems have made to David Cameron over the budget reduction strategy pale beside the concessions Labour made to the Tories - ceding the whole economic ground - years ago. If Labour is going to continue to obsess about 'betrayal' and 'selling out', it needs to start looking in a mirror.
Labour lost its soul in office. One of the sticking points in the Lib-Lab talks on which Labour was unwilling to concede concerned locking up the children of illegal immigrants. This pretty much says it all. There are a great many things that worry me about the Conservative-Lib Dem coalition but I am confident that we will end up a freer, more humane society as a result. And that is about as damning an indictment of Labour as it is possible to make.
Nonetheless, in terms of a future for the progressive left, we have grounds to be optimistic. There are four things we need to do to ensure that this coalition does not become a triumph for the right.
First, we must maintain lines of communication and co-operation. At Westminster, select committees will be a useful place to build alliances. With most of the more right-wing Lib Dems now holding office, the Lib Dems who hold the balance of power in these committees will tend to be of the left.
Second, it is vital that the new Labour leader is someone the Liberal Democrats can do business with. Returning to pendulum politics is neither desirable nor likely in the longer term. The UK has now embraced multi-party politics and can expect to follow countries like Canada and India, whose first-past-the-post voting systems no longer prevent balanced parliaments. If there is a balanced parliament again in May 2015 and the Lib Dems face the same obstinacy from Labour that they experienced this time, the Tories' position will only be stronger.
For the Liberal Democrats, their new ministers need to use their time and resources in office wisely. They may not have won every policy battle in the coalition agreement, but they can now commission civil servants under their control to fully research policy options.
One example worthy of urgent attention is a full study of the practicalities of land value taxation. A policy aspiration that goes all the way back to Lloyd George's People's Budget a century ago, there has been no serious attempt to implement it since the first world war.
Finally, the Lib Dems need to widen and deepen internal debate about policy and strategy. Party members need to be able to define themselves as Liberal Democrats while not signing up to everything the party says. The party needs a 'partnership in power' arrangement, building on the existing democratic decision-making processes.
In Scotland and Wales, the experience of coalition government led the Lib Dems to become more concerned about the practicalities of administration than strategic direction. We must not repeat that mistake. The risk is that Lib Dem ministers - and the media - will view any disagreement with government policy as an attack. Nick Clegg and his team need to be far-sighted enough to appreciate the virtue of dissent.
There is only so much constructive criticism the parties' internal processes will be able to handle, however, and for that reason the Social Liberal Forum needs to up its game as both an advocate of authentic social liberalism and as a genuine forum.
This is an exciting, scary time to be involved in politics. Now is not the time to wrap yourself in cosy slogans and old comforts. The Liberal Democrats in office are guaranteed to not get everything right, but as soon as the left begins to recognise that they can do a great deal of good, we will start to make progress.
James Graham is on the Lib Dem federal executive and an executive member of the Social Liberal Forum (www.socialliberal.net). Come to Red Pepper's fringe meeting at Compass conference, 'Class, Power and Ownership: Liberalism and its Limits'. Saturday 12 June, 1.30pm