A document leaked to the Sunday Times and bearing all the hallmarks of a genuine Foreign Office memorandum has revealed the extent of British unease at American military operations in Iraq.
It is very rare that such an extensive insight is available on such a crucial international issue. It will not please British diplomats to have their plans made public.
The document, dated 19 May, is an assessment of the British strategy in the run-up to the handover of power on 30 June.
It states: "The process is difficult and setbacks are to be expected. But we have a strategy to push progress forward."
The memo suggests tension behind the show of unity
The position outlined in the memo is at odds with the show of unity demonstrated again last month by Prime Minister Tony Blair and President George Bush at a joint press conference in Washington.
Under pressure from Conservative leader Michael Howard to outline differences, Downing Street has said that airing these in public would "undermine troops' morale".
The memo is critical of the American military approach. It says: "Heavy handed US military tactics in Falluja and Najaf some weeks ago have fuelled both Sunni and Shi'ite opposition to the coalition, and lost us much public support inside Iraq.
"The US have learnt lessons from this and are generally proceeding more cautiously."
It also admits that "there are signs of better organisation by insurgents and a reservoir of popular support, at least among Sunnis."
This assessment contrasts to the public coalition statements that the insurgents are "terrorists" and " foreigners".
But it also suggests there is other diplomatic tension with Washington. This emerges when it discusses two issues.
The first deals with options for either the deployment of more British troops to Iraq or the despatch of a British-led Nato headquarters group.
"If we go down either route we should ensure that we use it to maximise our influence over American military decisions, and that we can prevent US action, either at the strategic or operational levels, which would jeopardise our objectives," it says.
The other comes when the memo discusses the prospects for a Security Council resolution giving approval to the handover arrangements.
It stresses that Britain wants the Iraqi interim government to "have an effective veto over major operations".
Tensions have increased alongside attacks on coalition troops
"We still need to tie the US down to language that reflects these principles. But if we do so, and then give the French, Germans and Russians a genuine opportunity to offer views on the draft, the prospects look reasonable.
"This will require detailed senior level intervention with the US."
As to the issue of prisoner abuse, it again hints at problems with the Americans by saying, without giving details, that the Foreign and Defence Secretaries are "considering ideas for greater international involvement".
French diplomats will note with interest the British aim of getting the new resolution through the Security Council "ideally before the D-Day celebrations on 6 June (which will serve as some leverage on the French)".
Presumably this means Britain thinks that France does not want differences over Iraq to muddy the D-Day waters.
But, if France is not so minded, all it has to do is to delay the resolution beyond 6 June to put a spoke into the British wheel.
Overall, the memo appears to be a typically pragmatic Foreign Office assessment, listing the problems and some ways to tackle them.
It deals only with the period of the handover and its aftermath and therefore does not discuss the circumstances in which foreign troops might leave Iraq.
One of the most interesting passages deals with security post 30 June.
It confirms what senior officials have already told correspondents - that Britain wants the Iraqi forces to have an opt-out of military operations and will remain under Iraqi command.
There is also to be an Iraqi National Security Council, led by Iraqis but with senior "multi national force" representation.
The fact that these details are present in the document and are known to be the British position is one of the reasons why the memo appears to be genuine.
The memo admits the handover will not be easy and that "the summer months are bound to be difficult".
By October, it says, "we need to be well under way with election preparations, with Iraqis exercising control over their own government and over much of security, with supplemental money being turned into jobs and early results on the ground, particularly in Sunni areas, and the insurgents undercut by progress on all of those fronts."
That, therefore, is the hope and the plan.
The last line admits it is not easy but, importantly, it shows no wavering: "The task is considerable; the stakes are high; but it is imperative that we succeed."
The memo, according to the Sunday Times, was accompanied by a one-page supplement with "public lines to take" for British ministers.
The "line to take" is a staple of ministerial documents. It ensures everyone is singing from the same hymn sheet.
The interesting point about this "line to take" is that it does not reflect the memo. Instead, it blandly concedes only that "the security situation in Iraq is difficult."