Ed Miliband's vision of a new mass membership organisation is nothing more than a dream. The reality, as the hard data from today's British Social Attitudes survey shows, is that the party system in Britain is dying a long, drawn-out, painful death.

You can't blame the Labour leader for trying. His courageous bid to shape up the relationship between trade unions and his party might end up freeing him from the influence of the general secretaries.

The problem is it also might polish off Labour's hopes of raising anything like the funding levels it needs to fight effective general election campaigns. The question is whether he can persuade enough trade union members to switch from a proxy to an active role in the nation's politics.

It seems unlikely. Many union members join for selfish reasons: they want to take advantage of the negotiating position their union holds, and give themselves a degree of support in the event of redundancy or other trouble with their employer. At the height of the left-right clash, in 1983, just eight per cent said they didn't identify with a political party. Today that number has risen to 21%, according to the social attitudes survey. Party membership levels tell their own story. It's clear that political participation is suffering from a long-term decline.

The problem is not politics, though. What's so striking about the survey's findings is interest in the great debate about Britain's future is not fading. Thirty-two per cent are interested in politics, up from 29% in 1983. And while those believing it's important to vote have decreased in number slightly, there is a growing enthusiasm for finding alternative ways to engage in politics.

It is the establishment which is being rejected. Thirty-two per cent never trust the government, up from 11% in 1986. Roughly the same proportions are disengaged because they think it doesn't matter which party is in power, reckon MPs lose touch with their voters as soon as they arrive in Westminster and, ultimately, believe it doesn't matter which party is in power. Those thinking all this now number around three-quarters of the total, up from two-thirds three decades ago.

There is an appetite for politics out there, but it's not the kind the parties are prepared to offer. Had the coalition wanted to offer a genuine constitutional reform that would have commanded genuine majority support among British voters, it should have ignored the Liberal Democrats' pet project of Lords reform and instead introduced more direct referenda and come up with a bona fide recall legislation.

Neither of these options suit the party system which continues its stranglehold over British politics. The numbers are all there for politicians to see, but they're turning a blind eye to them. Instead we're left with Miliband pushing a fantasy world where union members queue up to back the Labour party. It's a noble idea, but it's not backed by the data we're seeing today.