He blinked. Tony Blair has devoted his career to defending the office of party leader from the sort of tinpot coup that last week drove him from power and soon from office. Yet driven he was. The master of control lost control.

For reasons that to the public must seem wholly opaque, a man whom it had just awarded a third election victory emerged from Downing Street looking tired, angry and resigned. His one hope of self-respect is to hang on for his 10th anniversary next May and somehow take revenge on the architect of his misfortune, Gordon Brown. The furious response of his supporters in the past two days, led by the former home secretary Charles Clarke, is too late to save him. The next nine months in Labour politics will be unedifying, but they will not be dull.

This shambles is what a country gets for having a dud constitution. Ejecting a quasi-president other than at the electorate’s bidding is messy. It is the more so since the Blair-Brown rift is not ideological and involves no issue of principle. Blair’s leadership was electorally solid and his policies, warts and all, were supported by his cabinet and MPs.

Despite Iraq, the polls suggest Blair would serve his party better than Brown at an election. Certainly they offer no evidence that a change of leader is electorally necessary. Brown is an unknown quantity starkly lacking in public personality.

This rift is personal, between two men who neither like nor trust each other. If Blair’s judgment has become warped by a craving for legacy and longevity, Brown’s is warped by gnawing ambition for his job. The shouted obscenities reportedly emanating from Downing Street last week bespoke no great issue of national interest. It was two men fighting eyeball to eyeball for power. Blair was right afterwards to apologise.

Brown, proximate cause of the row, did not do so. Such incidents strip government not just of dignity but also of all claim to public confidence.

Downing Street has long been the scene of conflict between No 10 and Treasury irregulars. Never has it so resembled a West Side Story knife fight between the Sharks and the Jets, with a plaintive rendering of I Want to Be in America from the master of No 10. The nation’s business cannot sensibly be conducted this way.

Prime ministers should never serve as long as Blair, or as long as Margaret Thatcher did before him. Exhaustion clouds decision. Egoism tears at personal loyalties and induces a yearning for change. Familiarity breeds contempt. A term limit of two four-term parliaments should be regarded as constitutional custom and practice, to avoid the trap into which both Thatcher and Blair have walked.

For the present there are only two ways of removing a resistant leader, assuming that he or she enjoys the support of the electorate and of a majority in the Commons. It is by open combat or private pressure. Brown claims a right to the succession conferred in a restaurant 12 years ago. That might pass muster in a private gentleman’s club but to enforce it against a resisting prime minister requires guts and panache. When Harold Wilson challenged Hugh Gaitskell in 1960, when Thatcher challenged Edward Heath in 1975 and when Michael Heseltine challenged Thatcher in 1990 they did so in the open, through their parties’ electoral procedure.

Brown has always been free to stand against Blair if he can secure the backing of 44 fellow MPs. He should have done so the moment last year when Blair said that he intended to serve “a full third term”, since Brown clearly regarded this as a breach of their private understanding. But then nor did Blair have the stomach for an open fight. He should have removed Brown from his Treasury power base to the Foreign Office after the 2001 election. He certainly should have done so when Brown’s conspiracy was blatant after the 2003 and 2004 party conferences. Both men let the other call his bluff.

Instead Brown opted for private pressure, conspiracy and bluff. He has schemed to undermine his boss from within, his ambition like Dracula coming out at night to howl with spin doctors and sink his fangs into any passing Blairite.

The chancellor has developed the greatest grudge in modern history, more visceral even than Heath’s against Thatcher. When Blair speaks, Brown does not clap. When Blair skirmishes with Cameron, Brown does not smile. He bears the emotional scars of a Scottish clan feud, as if enveloped in a torment of vendetta and intrigue. It has not been a pretty sight.

Until now the plotting has failed. The Brownites could not even stage a proper mass resignation last week, summoning chiefly a rabble of parliamentary private secretaries and not one cabinet minister. Most prime ministers would regard such a gesture as a fleabite. When Tory rebels tried to subvert John Major’s leadership in 1995 he threw down the gauntlet and put himself up for re-election, winning another two years in office.

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