John Rentoul: We've had a coalition since 1997

Contrary to the conventional wisdom, the British people are quite used to coalitions. After all, they were governed by the Blair-Brown coalition for 13 years before the present one. In our discussions about our forthcoming book on the New Labour governments, Jon Davis and I returned again and again to the relationship between Tony Blair and Gordon Brown. But it was not until the Conservatives and Liberal Democrats formed a government last year that we found a model to help us understand the period that had just passed.

Blair and Brown's rivalry and intermittent co-operation was like a coalition. It was more than mere personal manoeuvring over the right to the top job. It was more, too, than a conflict between strands of opinion in the Labour Party. It was also more than the latest manifestation of the historical tension between Nos 10 and 11 Downing Street – a tension that usually takes time to develop. This was a working agreement between institutionally and ideologically distinct parties, the Blairites and Brownites.

In Parliament, each party had its own whipping operation to organise its MPs. Brown's whips caused most difficulty for Blair during the House of Commons passage of bills to bring in foundation hospitals, university tuition fees and trust schools.

The two parties even had separate funding and polling arrangements. Lord Levy notionally raised money for the Labour Party, but the secret loans raised for the 2005 election were almost personal to Blair, while Peter Watt, Labour's general secretary, spoke of a secret "fund with no name" in the party's accounts at Brown's disposal even while Blair was leader. Philip Gould, the party's pollster, was personally answerable to Blair and distrusted by Brown, who used his fund to pay for his own private polling.

In government, important policy decisions on operational independence of the Bank of England, the euro, and NHS spending, were taken by the leaders of these coalition parties alone. Much official business was conducted between the two faction leaders or their trusted deputies. That, rather than Blair's "presidentialism", was the real reason that the Cabinet role was downgraded.

A New Labour coalition agreement even existed in the form of the Granita deal of 1994, when Blair ceded some control over economic policy and the wider domestic programme to Brown. The agreement was updated several times, notably at the Admiralty House dinner brokered by John Prescott in November 2003, when Blair undertook to hand over to Brown the following year in return for co-operation on policy. This was superseded by Blair's October 2004 declaration that he would fight the next election, but not the one after that, and his appointment of Alan Milburn as heir apparent. That deal was partially reversed in the "ice cream" pact by which Brown was restored to the dual leadership in order to fight the 2005 election, and then fully negated by the Brownite coup of September 2006.

When Blair stood down nine months later and Brown took over, the new prime minister continued to operate his government as a coalition with Blair's followers. After trying to distance himself from his predecessor, Brown appointed two of the most Blairite, Peter Mandelson and Andrew Adonis, to his Cabinet.

There are differences between the Blair-Brown coalition and the present one. The main contrast is that relations between the coalition partners in the Labour government were characterised by mistrust, hostility and personal ill-feeling. Senior civil servants tell us that the conduct of government has been politer and more straightforward since the 2010 election than it had been for the preceding 13 years. Mind you, that difference has been rather eroded in recent weeks.

The second important difference is that Nick Clegg is not agitating for David Cameron's job and has no prospect of getting it. The forces holding this coalition together and those pulling it apart are different. They are related to the third difference, which is that the Blairites and Brownites never competed in general elections. (Although there were furious internal battles over the selection of parliamentary candidates, most of which were won by the Brownites.)

Yet many of the dilemmas of coalition that are explicit now were implicit then. Brown, like Clegg, had to judge the balance between differentiation and working together. Brown had to stay within a notionally single party's policy, although he had the advantage of a reputation as a successful chancellor presiding over sustained economic growth. Until recently, Clegg refused to use his greater freedom to assert his party's separate identity, preferring to stress how united he and Cameron were on policy. In fact, in the heady early days of this coalition he used to quote Tony Blair in private, saying: "It's worse than you think: I believe in it."

Brown was never so enthusiastic, in public or private, about the Blairites' policies, but he and Blair both suffered when he sulked, and they both benefited when they publicly united in the 2005 election campaign. That is the problem that Clegg now faces. He has made himself unpopular with his party's former supporters by trying to show responsibility and unity, but if he now disagrees with the Conservatives that is likely to make him more unpopular still, because most voters say that they like the idea of politicians working together. That seems to apply whether they belong to notionally separate parties or not.

After one year of this coalition government, the surprise is how little fuss this supposedly freakish novelty has caused, and how easily the British constitution has adapted to it. Benjamin Disraeli said, "England does not love coalitions," and that was said to be one of the reasons why the status stayed quo in the referendum on changing the voting system. But, actually, we have been living with coalition government for much longer than the past 12 months.

'The Blair-Brown Coalition', by John Rentoul and Jon Davis, will be published by OUP next year