Shady corridors, smoke-filled rooms and back-room deals are hardly what comes to mind when Ed Miliband talks of the “new politics.”

But that’s exactly what you’ll find at Labour’s national policy forum (NPF) — though these days smokers stand outside.

At dinner on Saturday night, Harriet Harman said it should be renamed the National Policy Festival. “And we don’t need Dolly Parton, because we’ve got Ann Black!” she cried, referring to the legendary former chairwoman of Labour’s NEC.

Only Labour bureaucrats would host a festival in Milton Keynes. You might not know it but, in some places, watching paint dry or Liam Byrne can be a riveting experience.

When the NPF was established in 1997, “modernisers” said it was about uniting the party. The left said it was designed to undermine conference and the party executive — and push through unaccountable decisions.

Amendments to draft policy documents are sent in by local party branches and affiliates, and taken forward by their reps if they so please.

The next hurdle is the “consensus wording” — where policy advisers approach you toting bits of paper and ask you to ditch your amendments in exchange for compromise changes.

One man who knows all too well the way these gatherings end up is veteran activist Jon Lansman, of the Campaign for Labour Party Democracy.

So this year, after trying in vain to get an office in the building, he parked a camper van outside the conference centre.

The Democracy Van offered a vigilante advice service to left-wing delegates. A few frontbench MPs were seen coming and going too.

Splashing out on hotel rooms and vol-au-vents can’t come cheap for cash-strapped Labour. After another weekend of anti-climax, frustration and compromise, there will be renewed calls to scrap the whole show — and return to policy-making at annual conference.

That’s where decisions ultimately rest if a consensus can’t be reached — even if the forum votes an amendment down it goes to conference as a minority position if it gets the support of 25 delegates.

Union reps have said the atmosphere is vastly improved under consensual chairwoman Angela Eagle. It’s moved on from the days when left-wingers were mocked on stage by Blairite Tony Robinson.

But that doesn’t mean activists will stop fighting.