Peter Snowdon: High stakes ahead in Westminster's shotgun marriage

In both world wars, Britain had a coalition government when the main parties felt compelled to work together in adversity. The only other peacetime coalition was a continuation of David Lloyd George's government between 1918 and 1922, a legacy of the First World War. For the old Liberal Party, it spelt the end as a party of government. For the Conservatives, it heralded an age of dominance.

Cameron's decision to invite the Liberal Democrats to join a coalition could be the most audacious political move of our era. Much has been written about this being Cameron's "Clause Four" moment, completing the journey to wrench his party back to the centre ground. However, it was not achieved in the wilds of opposition, but when he was on the cusp of government following the electoral stalemate of May 6.

If his gamble pays off over the next five years, there will be echoes with Benjamin Disraeli's embrace of parliamentary reform in 1867 or Stanley Baldwin's decision to stand aside in 1924 and allow the Labour Party to form its first government. Both manoeuvres enhanced the Tories' electoral prospects in the long-term.

Indeed, the potential benefits to the Conservatives are already obvious. Although Cameron failed in his mission to lead his party back into office with a majority of its own, he brought them the precious opportunity to exercise the levers of power for the first time in 13 years. As one Minister put it: "The truth is that you can't fully convince people that you have changed in opposition, as they have only heard you say things, not do things." Cameron is now showing the electorate how "modern, compassionate" and liberal Conservatism works in practice.

Dissenting voices on the Right of the party have been aggrieved that the inheritance tax cut has been shelved and disillusioned that Liberal Democrat policies have been adopted, but they neither have the numbers nor the powerful advocates to marshal opposition in the short-term.

The leadership's advantage lies in the immediate loyalty of the 148 new Conservative MPs. If the Prime Minister manages to keep them onside – either through the powers of patronage or persuasion – he will have gone a long way to reinforcing the foundations of the coalition.

Another reason for the Tory leadership to be sanguine lies in the fact that Nick Clegg and senior Liberal Democrats are striving to make the coalition succeed, despite the embarrassment after Treasury chief secretary David Laws resigned over his expense claims.

Although Clegg admitted that his decision to enter government "caused some surprise and with it some offence" in his party, the prize of entering government and being able to implement policies for the first time in more than 80 years was too alluring.

Whatever the strategic opportunities this new partnership affords, it is nevertheless a shotgun marriage. The expediency of a hung Parliament forced the two parties to work together. And while the agreement was forged in a spirit of co-operation and the chemistry between Cameron and Clegg appears strong, fundamental differences on policy have not disappeared.

It is here that the last peacetime coalition government became unstuck. The post-First World War coalition under the last Liberal Prime Minister, Lloyd George, became deeply unpopular when it introduced the "Geddes Axe" in 1922 to control the spiralling national debt.

Mounting resentment to spending cuts contributed to several years of industrial unrest and enhanced the electoral prospects of a nascent

Labour movement. The pressures within and without the coalition became too great, and as the dominant partner Conservative backbenchers rebelled against their leadership and pulled the plug.

At the famous meeting at the Carlton Club on October 19, 1922, Tory MPs voted by a margin of two to one to leave the coalition. Disenchanted with Austen Chamberlain's compliance in the coalition and disgusted with the behaviour of Lloyd George as Prime Minister, the parliamentary party sought to reassert their independence. In one bound, the Tories had released themselves to fight their new opponents, the Labour Party, and sealed the fate of the Liberals as a party of government.

History does not necessarily repeat itself. The realignment

in British politics after Britain's last peacetime coalition government occurred in very different circumstances, not least in the wake of a world war that dramatically changed the terms of political debate.

Yet whether this coalition succeeds or fails, the stakes for all three parties are extremely high. For the Tories, there is an opportunity to hug the centre-ground, while the Liberal Democrats can demonstrate their credentials as a party of government. In the tough times ahead, the pressure of events and policy disputes may prove too great. Meanwhile, a revived Labour Party under new leadership will hope to capitalise on what they believe to be a marriage doomed to fail. If it succeeds, however, they could be trapped in opposition for years to come.

Peter Snowdon is the author of Back from the Brink: The Inside Story of the Tory Resurrection published by HarperPress.