Professor Matthew Flinders: Happy together for now but will it turn out to be a shotgun wedding?

I can't help but thinking about that advert as I ponder the coalition agreement between the Liberal Democrats and Conservative Party. Even though my heart tells me that sometimes opposites attract, I cannot help but feel that a rather messy and potentially expensive political divorce is likely.

The General Election was a curious event. It was clear that "the people" had spoken but it was very hard to actually understand what they had said. The election results suggested that the public did not have a clear preference for any party, resulting in a bizarre courtship ritual as the two main parties attempted to woo the Liberal Democrats in order to tip the balance of power in their favour.

For those schooled in the British political tradition of clear majorities, strong government and adversarial politics this very public display of horse-trading and blatant gamesmanship was positively distasteful. But now the pre-nuptial agreement has been agreed and signed, the marriage vows exchanged and the wedding pictures taken of the groom and groom smiling and joking in the Downing Street garden, the time has come to inject a degree of realism into the debate.

Although both partners were keen to present this as a "historic and seismic shift in British politics", it is really little more than a grubby shotgun wedding.

It is also a relationship in which both sides have been thrown together and must now learn to live together under unprecedented pressures. The financial crisis, the lack of public confidence and trust in politicians, a number of major global challenges and increasing public expectations will either forge a coalition of diamond-like strength or cause it to implode within 12 months.

My money is on the latter. Not because the coalition partners have so many glaring policy differences, not because the machinery of government is not prepared for the challenges of coalition politics but because of the British political tradition. It is the assumptions and expectations about how politicians should behave that will seal the fate of the coalition simply because it projects an almost tribal mentality across society in which compromise is viewed as a sign of weakness and being keen to negotiate with other parties a form of betrayal.

The lessons from history and overseas suggests that successful coalitions will generally emerge when formal procedures for information sharing and signing off decisions exists; where the junior coalition partners, in this case Nick Clegg as Deputy Prime Minister, enjoys additional resources to allow them to play a full and active role in proceedings; where a pool of trusted special advisers exists to help resolve coalition management issues; and where clear dispute resolution procedures are present.

Although the Cabinet Office has gone to great lengths to try to prepare for the coalition challenges, these basic but essential institutional features are not in place. Sir Humphrey is undoubtedly going to be on a steep learning curve.

As with most contracts, the devil is very much in the detail. The agreement is heavy on broad policy positions and statements of good intent but light on specific detail.

The future of Trident, student tuition fees, the European Union, electoral reform and immigration are major issues where it is hard to identify any common ground. You can arguably fudge the existence of fundamental policy differences during the honeymoon period but they are certain to loom large in the not too distant future.

The honeymoon period will also be very short, but this is not necessarily a bad thing. If sweeping cuts are to be made in public spending, or if taxes are to be increased, then it is in the interests of the new government to wield the knife sooner rather than later in order to be able to blame the previous government.

In many ways the existence of a coalition is useful to both party leaders as they can use the need to satisfy their coalition partners in order to deflect criticisms from within their own parties. This is particularly valuable for David Cameron who must somehow contain and manage the Right-wing of his party. For Mr Clegg, the real challenge is maintaining a distinct party identity while at the same time abiding by collective responsibility.

Yet the biggest challenge for the coalition is cultural. Coalition politics might work reasonably well in New Zealand, Ireland, Denmark and Germany and even in the Scottish Parliament and Welsh Assembly, but these systems have either evolved or been created in order to deliver a quite different form of politics.

It is not just that the institutional mechanisms are in place in these systems but because the political culture cherishes and respects compromise that coalition politics works. The need for mutual trust and understanding between coalition partners, especially the leaders, is not only understood but generally in existence.

The British form of "yah-boo" politics with its emphasis on "attack, attack, attack" lacks the cultural pre-requisites for successful coalition politics. Whether this is a good or a bad thing is a moot point but irrespective of whether they really "want to be together", the chances of a long and happy marriage for Mr Cameron and Mr Clegg are slim.

Professor Matthew Flinders is deputy head of politics at the University of Sheffield.