Six days ago, Tony Blair conducted an interview with The Times in which he sought to curtail speculation about his future while declining to do more than send a coded signal about the timing of his departure. We stated here then that while his preference was “understand- able”, he would be “sorely mistaken if he assumed that he has all the cards” and that he could not “expect Delphic hints, nods and winks or a vague pledge about providing ‘ample time’ to be enough for his closest colleagues”. So it has proved. There has been a lively debate about telepathy in scientific circles this week. Telepathy is not the normal way for a prime minister to communicate to his political party.

As a result of that interview, in very large part, matters have moved yet further beyond Mr Blair’s control. He has been embarrassed by a leaked memo which set out a risible plan for a euphoric exit; obliged to allow David Miliband, the Environment Secretary, to broadcast that the conventional wisdom that Mr Blair would leave office next year was “reasonable”; and seen an alleged formal timeline surface in a newspaper. A junior minister and six parliamentary private secretaries have walked out on him. As dignified departures stand, Mr Blair’s plight appears less Songs of Praise than Hell on Earth.

Mr Blair will not, however, be the only politician to feel the heat if the current atmosphere cannot be cooled. The Labour Party spent much of yesterday looking as if it had acquired a collective deathwish. Options for dates upon which the Prime Minister might announce his resignation — September 2007, July 2007, March 2007, January 2007, next month, today — were being traded as if an unwanted item at a Dutch auction. It seemed that the proposed supercasino had already been built and put somewhere in the Westminster area. This is utter madness. Order, decorum and a degree of simple clarity have to be restored.

The task is not one for Mr Blair alone. In reality, authority in this domain has slipped away from Downing Street over to the Treasury. If Gordon Brown decided that he wanted Mr Blair to go forthwith, he could easily conspire to bring about that outcome and quite quickly. What he could not do, though, is credibly claim to have played no part in his demise. While the Prime Minister is not as popular as he once was with either public or party, he is not entirely without his admirers either.

The example of the Conservative Party, which is only just beginning to recover from the trauma of Margaret Thatcher’s political assassination 16 years ago, should send shivers down the Labour Party’s spine.

It is, therefore, in Mr Brown’s interests as much as Mr Blair’s to bring an end to this leadership crisis. They have to be seen together and speak as one, to communicate that a settlement has been reached to which each is bound and to ensure that while the change, entirely properly, will involve a significant shift in political style it will not be one which — in domestic or foreign policy — triggers a fundamental transformation in substance. Other members of the Cabinet have to be brought into this compact, partly, to be frank, as witnesses, but also to ensure that it is not seen as a private treaty from which the Labour Party is excluded. There has to be The Deal (III).

It is not absolutely necessary for the Prime Minister to name a precise date — January 11? March 11? April 25? — for the formal transfer of office. He should say, personally and publicly, that the imminent party conference in Manchester will be his last as leader. This would defuse much of the tension. It should also be patently obvious to all, party process aside, that Mr Blair and Mr Brown are comfortable with the agreed calendar, whether it be before or after the elections next May. If that is achieved, Mr Blair can spend a few final months in office setting out the coming challenges that he believes Britain will face in a series of serious speeches (and not tacky media stunts), while Mr Brown can prepare properly for the assumption of power.

None of this is impossible to secure. The notion that the official machine will grind to a halt in these conditions is abject nonsense. If Whitehall knows that a policy initiative is blessed by Mr Blair and Mr Brown, then it will proceed with the implementation. Civil servants would not twiddle thumbs in such circumstances because they were unsure whether the Campaign Group of hard-left Labour MPs was enthusiastic about the proposal concerned. The British constitution is a device of the lightest plastic, not the hardest iron. It can be extremely malleable if those in high places are ready to be flexible. Mr Blair must appreciate that he has to bend. Will Mr Brown contort as well?

He certainly should. For all of their disputes over the years, the competing interpretations of what was said first in a restaurant in Islington in 1994 and then in front of John Prescott at his Admiralty Arch apartment a decade later, Mr Blair and Mr Brown remain locked in a symbiotic political relationship. Granita has long closed and the Deputy Prime Minister is defunct also. The past must not become a prison.

The future of the Labour Party, this Government and Britain as an actor in world affairs depends on the two men being determined that one tenure will not end in a bloody shambles while another would start stained by factional chaos from which it never recovers. They have hours, not even days, never mind weeks, to settle on an accord, shared with others, from which there can be no recasting, retreat or revision.

Jonathan Powell, the Prime Minister’s chief of staff, once observed that Mr Brown was akin to a figure in a Shakespearean tragedy, a prince who would never wear the crown. Yet it is Mr Blair who now needs his rival to support him. If Mr Brown concluded, in the spirit of Macbeth, that “if it were done when ’tis done, then ’twere well it were done quickly”, the Prime Minister is surely destined to be his Duncan. The Chancellor should, nevertheless, remember what was the ultimate fate of a once great Scotsman, Macbeth.