Tim Bale: Cable has power to speak out, but will he push the coalition to breaking point?

But Vince Cable’s decision to go public with his view that David Cameron’s setpiece speech on immigration was “very unwise” and risked “inflaming extremism” pushed things about as far as a Minister can go without resigning or being sacked. Had this been a traditional one-party government, it is inconceivable that he could have made those remarks and still kept his job.

The fact that Cable continues in his post as Business Secretary is surely the best illustration yet of the huge power that a hung Parliament hands to any party able to act as a kingmaker. But the fact that Cable continues to feel it necessary to kick against the pricks is proof positive that the Lib Dems did not make anywhere near as much of that position as they could or should have done.

To understand why Cable can get away with it, one has to go back to the day after the night before that was May 7, 2010. The election left the Tories as the largest single party in the House of Commons but not the most powerful.

It was the Lib Dems who, despite their relatively small haul of seats, had the greatest “walk away value”. The Parliamentary arithmetic meant – and still means – that they were “pivotal”. Barring an unlikely “grand coalition” between the Conservatives and Labour, no government could form without their active participation or at the very least their tacit agreement not to defeat it on a vote of confidence.

Yet, whether through naïveté or because their leader had already made up his mind who he wanted to share power with, the Lib Dems hopelessly underplayed their hand. Forget the complaints of the Tory right that David Cameron gave too much away: given the underlying weakness of his position, he did a pretty good job.

True, the coalition agreement obliged the Conservatives to scale back some of their ambitions. But many of those were unrealistic anyway. On signature issues like deficit reduction, immigration, and the retention of Britain’s independent nuclear deterrent, they weren’t forced into a retreat. Nor, incredibly, did they have to give any of the big offices of state to their junior coalition partner.

Most mainland European parties, on finding themselves in the Lib Dems’ position after an election, would have demanded either the Treasury or the Foreign Office, plus another major high-profile “bread and butter” department like Health or Education. Not the Lib Dems. They secured the deputy premiership – a post with potential but one hitherto regarded as at best a consolation prize, at worst a joke. And they got the Department of Energy and Climate Change, which will impress few outside the ranks of the ecologically-converted, along with the post of Chief Secretary to the Treasury, thereby associating the party closely with spending cuts.

Last, and very probably least, they got Vince Cable’s own Department of Business, Innovation and Skills. This involved taking responsibility for raising the cap on university tuition fees that the Lib Dems had previously pledged to oppose and helping to clamp down on the immigration that they previously argued, whether some people liked it or not, was in Britain’s best interests

Had the Lib Dems instead done a deal with Labour, they would almost certainly have been given bigger and better cabinet jobs. But that would have meant serving in a minority administration relying on the support of the nationalist parties. Whatever they said in public, most of those closest to Nick Clegg – the so-called “Orange Bookers” whose views on a whole range of issues make them virtually indistinguishable from (again so-called) “progressive Conservatives” – ruled out this option right from the start.

Not so, however, Vince Cable. As the last, best hope of his party’s social democrats – those MPs and activists who were always emotionally and ideologically more inclined to work with Labour, particularly if Gordon Brown could be persuaded to go – it was (and still is) important that he be convinced a Con-Lib coalition could not only work but was the right thing to do for the country and for the party.

Vince Cable, then, is effectively the Liberal Democrats’ swing voter. If they can keep him in the Government, they have a reasonable chance of keeping the whole show on the road. Both the Prime Minister and his deputy know this, which is why they will continue to allow him unusual leeway – at least for now. But even if their patience is infinite, Cable’s may not be. If he keeps doing what he’s doing, it may not be too long before he pushes the self-destruct button.

Whether, in doing so, he takes the whole coalition down with him, as he once infamously threatened to do, will be fascinating to watch.

Tim Bale is Professor of Politics at the University of Sussex and author of The Conservative Party from Thatcher to Cameron, now out in paperback.