Mark Field MP: The cost of keeping the Liberal Democrats inside the Coalition may undermine Tory candidates' election prospects

Mark Field is the Member of Parliament for the Cities of London and Westminster. Follow Mark on Twitter.

Regardless of post-Budget and party donor squalls, I reckon it still remains a sensible working assumption that the coalition will sustain for the full five year term of this parliament. Incumbents are notoriously difficult to prise out of Downing Street. Against all odds (or so it seemed) John Major survived for virtually a full term after the collapse of his economic policy in September 1992; similarly even Gordon Brown could not be ousted from the Premiership in spite of apparently perennial terminal crises in the quarter-decade from October 2007. So while Mr Cameron has simultaneously been under fire as not being Conservative enough (from some on his own side) and as too Conservative (from most detractors), my instinct is that the nation feels a sense of resignation that the coalition is the best option we have, particularly when the alternative bears the face of Ed Miliband and Ed Balls. But what of the political cost of holding together this unlikely blue/yellow pact?

To those with government jobs coalition has proved surprisingly congenial. Perhaps understandably that is not a feeling universally shared by those on the backbenches and those tensions will most likely grow.  Nick Clegg’s instinct, entirely understandable in the circumstances, is to be seen as the leader uniquely capable of holding his parliamentary Party tightly together. The strain on the loyalties of many of the fifty-seven Lib Dem MPs has at times been tested beyond breaking point, however, especially for those without prospect or desire for ministerial office.

Put yourself in the shoes of a sixty-something, centre-left Lib Dem MP, who increasingly disapproves of much of the coalition’s policy programme (and certainly dislikes the vocal local opposition and accusations of betrayal he or she is made consistently aware of in correspondence and at surgeries). Imagine then that this not untypical MP has decided not to stand at the next General Election. Inevitably he or she will ask why not spend the last few years of parliamentary life enjoying the freedom to speak his/her mind openly as an Independent Liberal Democrat on the Opposition benches.

The other main category of Liberal Democrat MPs whose loyalty has been sorely tested are those from the 2005 or 2010 intake, who won their seats from Labour in parts of the UK with little Liberal tradition, where outright opposition to issues such as tuition fees was crucial. I suspect several such sitting Lib Dem MPs may well be weighing up the benefits of defecting to a Labour Party that is moving leftwards and taking up a populist stance in opposition to public sector reforms. They will quickly conclude that their chances of holding their seats under coalition colours are between zero and nil.

Nick Clegg probably regards any diminution in the parliamentary strength of his Party as little short of a disaster. Yet the truth is he likely faces an unpalatable choice of holding the coalition together or keeping his Party intact. The corollary of this dilemma thus far has been a watering down of key pieces of legislation to placate his troops. This has led to a mess on tuition fees, NHS reform and welfare. The notion that Liberal backbenchers can extract concessions or, in some cases, be given the freedom to vote as they wish on crucial coalition business, when their Tory counterparts are told in no uncertain terms to tow the line, will continue to lead to enormous resentment in backbench Conservative quarters.

So by the beginning of 2014, I should not be surprised if, in a bid to ease party tensions and disentangle the two partners in advance of the election, the Liberal Democrat leadership is given licence to allow ten or fifteen of its backbench MPs to operate under an unofficial ‘supply and confidence’ arrangement. This may involve a commitment by this section to support key legislation such as the Budget, in return for the freedom to vote as independent Liberal Democrats on other matters. This month we have already had a preview of how this might take shape, with a bid by five Liberal Democrat MPs, led by John Pugh and Andrew George, to derail the Health Bill before its final hurdle.

As the General Election approaches, if such an arrangement were to come to pass, those hapless Tory candidates fighting such Liberal Democrat rebels may find themselves in the bizarre position of defending the government’s record against an incumbent opponent who has licence to distance himself from a coalition of which he is a part, having had licence to ‘vote with my conscience’. When the penny drops that this would undermine Conservative chances in key target seats, and thus the possibility of a Tory majority, coalition tensions will intensify.

Furthermore, the boundary changes - which will see the number of MPs reduced from 650 to 600 - will be of net benefit to the Tories 2015, but not in my view by as much as party managers at CCHQ presently calculate. New boundaries are also likely to undermine what psephologists refer to as the double incumbency effect – the boost to first-term MPs when they stand for re-election. At the general elections which followed the big landslides of 1983 and 1997, there was a conventional 2% swing to the Opposition party, which only garnered fewer than half of the anticipated gains in seats because of this double incumbency effect. One of the unintended consequences of the wholesale boundary changes that take effect in 2015 is the negation of much of the double incumbency boost which should otherwise have flowed to the Tories.

I reckon Downing Street has by now worked through the numbers and realised that a wafer thin Tory majority is as good as Mr Cameron is likely to get in three years’ time. If he is faced with a choice of relying for a workable majority upon already unbiddable backbenchers or continuing the coalition (I do not see the Lib Dems dipping much below thirty seats at worst) the latter option will probably be pursued, which is why Downing Street is probably mindful now of the need to keep the Liberal Democrats on side.

Tory strategists should not be complacent about the benefits of coalition, however. While the notion of consensus as represented by the current government has on balance been regarded positively by a general public tired of politicians’ synthetic dividing lines, it is increasingly coming to be despised either as a conspiracy against the expression of choice by the voters or as a convenient mechanism for the jettisoning of manifesto commitments. That sense of democratic illegitimacy, if convincingly compounded by a Labour narrative of Coalition economic recklessness, could yet prove compelling.