By Paul Reynolds
BBC News Online world affairs correspondent
Normally, missives from ex-diplomats about how policy has gone wrong are given as much attention as ranting from ex-foreign correspondents about how news has gone wrong - virtually none.
Blair-Bush policies have upset former British diplomats
But a letter from 52 former senior British diplomats will have a longer shelf life given the unprecedented numbers of signatories, the language used and the publicity stirred.
It criticised UK Prime Minister Tony Blair's close ties to the "doomed" US foreign policy for the Middle East and urged him to start influencing the White House to change its views or to stop backing them.
The ex-diplomats tapped into a current of public concern about the problems in Iraq.
"The charge that they are just old buffers and Arabists from the 'camel corps' won't stick," said Rosemary Hollis, head of the Middle East programme at the Royal Institute for International Affairs in London.
The list does include many Arabists and the letter was organised by one of them, Oliver Miles, a former ambassador to Libya, Luxembourg and Greece. He is now a consultant for businesses seeking to set up in Libya and elsewhere in the Middle East, including Iraq.
It was interesting that the letter concentrated first on Israel and only then on Iraq.
Foreign office Arabists have a particular hostility towards Israel, going right back to the 1930s and 1940s when Israelis overturned British policy in Palestine, then under a British mandate.
Indeed, the trigger for the letter, as it says itself, was the news conference by US President George W Bush and Mr Blair in Washington during which they agreed that the Israeli "disengagement" plan would not stop future negotiations.
But there were also signatures of diplomats who had served in Europe (a former ambassador to Germany among them) and elsewhere.
One of the non-Arabists is Sir Crispin Tickell, former British ambassador at the UN. He was there when the first Gulf War was fought against Iraq in 1991.
"Oliver Miles sent out an e-mail last week," he told BBC News Online. "I told him I would help though I did not see the actual text since I was going to China.
"It is absurd to say this is just an Arabist letter. I am not one myself. My concern was the status of the United Nations.
"The invasion of Iraq was illegal. It is the worst mess diplomatically in my lifetime with the possible exception of Suez.
"As for the Arab/Israel issue, we had hoped that the roadmap [peace plan] might make progress if the Americans had displayed leadership and drawn the line with Israel. We have instead seen retrogression."
Measured government response
Conscious of the weighty opinion expressed by so many diplomatic knights and near knights, the British government has adopted a careful response, enunciated first in an interview on the BBC by Foreign Office Minister Mike O'Brien.
He took the line that he did not know what the fuss was all about since the government, too, shared the aims of a two-state solution between Israel and Palestine, and a free Iraq.
"They seem to be advocating a policy and that we should follow it on the Middle East, but we are following it. Then they criticise us for doing it," he said.
According to Dr Hollis it is highly likely that the opinions of the retired diplomats are mirrored by serving diplomats.
"Critics of foreign policy inside the Foreign Office have gone very quiet," she said.
"There was an attempt a few years ago by a group still working there to complain about policy towards Iraq and Israel but they were told they could forget their careers if they went public.
"The Arabists have seen what has happened in the state department. They have been totally marginalised by the neoconservatives who regard them as bleeding-heart liberals who have gone soft on the natives.
"So this letter probably speaks for a body of opinion inside the Foreign Office as well."
Something similar happened before the Iraq war when a former British Chief of Defence Staff, Field Marshal Lord Bramall wrote to the Times warning that an invasion would pour "petrol rather than water" on the flames. This was felt to be a warning from serving officers as well.
Attempt to influence
The letter therefore goes beyond an expression of frustration by people no longer in the driving seat.
It is trying to have an impact on policy in a new way because the old way has proved ineffective.
The fact is that British foreign policy under Tony Blair is very much made in the prime minister's office, just as it was under Margaret Thatcher.
Mrs Thatcher's contempt for the Foreign Office was legendary. She would have thrown this letter into the Downing Street bin. Mr Blair does not have such contempt but he knows his own mind and also has a foreign secretary in Jack Straw who thinks like him.
That leaves officials who think otherwise very isolated.
This partly explains why their colleagues who can now speak out have done so.