The distinguished diplomat was barracked.
Chatham House is the epicentre of the British establishment, as famed for its associations with the security services as for its gentlemanly rules of press access. An autographed portrait of the Queen hangs in its oak-panelled entrance.
Yet Johnson, who had come to try to mend fences with stealth-bomber sceptics in London, was left shaken by a string of critical questions.
At one point, he was reduced to accusing a member of the institute of anti-Semitism, for asking if the US was willing to stand up to its "Jewish lobby" (not Israeli lobby) and impose a peace in the Middle East.
A retired diplomat in the audience won a thunder-clap of applause when he countered that it was "absolutely outrageous" to equate criticism of Israel with anti-Semitism. "I deeply deplore the slur you have cast on my colleague," he said.
Many would find it equally outrageous to equate all Jews with Israelis. But the one-sidedness of US policy on the Palestinian question has long-acted as a lightning conductor for wider discontent.
And above the Atlantic calm of US-UK diplomatic relations, there is certainly electricity in the air.
British subjects continue to
languish at Guantanamo Bay
It is nine months since the fall of Baghdad, and British diplomacy has yet to win the release of the UK's Guantanamo prisoners, or hold President Bush to his war-time promise to pursue peace in the Middle East.
It has also proved unable to win much in the way of business contracts in post-war Iraq.
Underlining such demonstrations of British powerlessness, is a fear that Iraq may not mark the end of unilateral US foreign policy adventures, but the beginning of a whole new phase. In this regard, Johnson's words were not reassuring.
"We must bring about a fundamental change in the human condition in the Middle East," he said. "When people realise that freedom is their birthright, terrorism can be defeated and a safe world can be created for all its citizens."
"We must bring about a fundamental change in the human condition in the Middle East. When people realise that freedom is their birthright, terrorism can be defeated and a safe world can be created for all its citizens."
US embassy, London
His sentiment was echoed by the US vice president Dick Cheney two days later at the World Economic Forum in Davos, even as his administration was straining every sinew to prevent an early ballot in Baghdad.
But is the world any safer now that the US is projecting its political and military power into the Middle East?
No, says Professor Paul Rogers of Bradford University.
"One of the major reasons that Al Qaida staged the September 11th attacks was to draw US combat troops into a guerrilla war in Southwest Asia, particularly Afghanistan," he told Aljazeera.net.
A UK expert says 11/9 was
meant to draw the US to SW Asia
"They failed because they didn't bargain on the US using the northern alliance as its ground troops.
"But as it has become clear that Iraq, a key Arab nation, will be a client state with major US military forces there for a long time, the Al Qaida belief has grown that this will be good news for their strategy. In the long term, they believe it plays into their hands."
Vital national interest
So why, ask the foreign policy wonks, has Britain gone along with it? What is the vital national interest which requires the commitment of thousands of British troops and billions of British Pounds?
According to Rogers, it is not primarily about oil because Britain is self-sufficient. But that won't "last forever," he qualified.
So why, ask the foreign policy wonks, has Britain gone along with it? What is the vital national interest, which requires the commitment of thousands of British troops and billions of British Pounds?
"Privately, the British know full well that the US is in the Gulf for at least the next 30 years just because the region is so incredibly important."
Even taking this account though, Rogers argues that the UK's interests are higher in Iran than in Iraq, and points to British engagement with Tehran as evidence.
Dr Charles Tripp, an author on Iraq and reader in Middle East Studies at London's School of Oriental and African Studies, argues that the real reason for what he calls Blair's "poodle-like" behaviour is a shameless pursuit of power.
"It is the belief of most British prime ministers that it is important to be at the top table, even if you are there as an invitee of the Americans," he told Aljazeera.net.
Dr Charles Tripp says Tony Blair
is shamelessly pursuing power
"Among the Whitehall establishment, it has become a conventional wisdom that it is better to be first among the US's allies than lumped in with Old Europe, even if that sometimes involves being put in a rather humiliating position."
And there lies the rub. Tony Blair's apparent ceding of an independent foreign policy has not won him any tangible concessions from the US. But it still rankles with many of his supporters and, Paul Rogers says, a significant minority of the establishment itself.
The situation is not helped by the lack of an articulated exit strategy from Iraq.
"If the Americans decide they want to get out," Tripp said, "for whatever reason, then the British will have to go along with them. You couldn't envisage them staying on after the Americans had gone. That would be very weird."
"But it's also very unlikely that the Brits would get out before the Americans because that would look like Tony Blair was pulling the plug on the Alliance and he certainly wouldn't want to do that."
All of this leaves the gentlemen and women of Chatham House stuck between a rock and a hard place. Tripp believes that the War on Terrorism may prolong the tensions in the "special relationship" between Britain and America for some time to come.
"It really is a strange war, because if, as President Bush says, it is one which will never end, then how will we be able to tell if we've won?"
Dr Charles Tripp,
London School of Oriental and African Studies
"It really is a strange war," he reflected. "Because if, as President Bush says, it is one which will never end, then how will we be able to tell if we've won?"