There used to be a game at particularly drunken 1930s house parties - I must have read this in PG Wodehouse - in which one person would leave the room and the remaining guests then tried to remember who it was. Even the most sober reader, though, may have difficulty calling to mind the present US ambassador's name. The explanation is simple, however. There isn't one. America has not had an ambassador here for five months. Not that, in recent years, you would have been much the wiser if there had been. Britain may be Washington's most devoted ally, and the London posting may be one of the most prestigious in the American foreign service, but the last US ambassador in London, William Farish, was so low profile that most people here were unaware of his presence or his departure.  Ambassador Farish was not the first envoy to get his job for services rendered - he was for years the Bush family's private banker - and he will doubtless not be the last. But the point was not that he was a political appointment rather than a career diplomat. It was that he was the original silent envoy, and his anonymity - save in bloodstock circles - came at a heavy political price.  It meant that, throughout one of the most demanding periods of modern transatlantic relations, America lacked a strong voice and presence on this side of the water. This was a double deprivation. It was a loss to Britain, since it left Tony Blair to take all the hits while attempting to mediate US policy in this country. And it was a loss to the US, because there was no one with the clout to mediate Britain's views back to the American administration and people.  You could argue, as some do, that in the networked world of the 21st century, ambassadors are not as important as they once were. And you would be right. Obviously when Blair and George Bush can do a video conference any time they choose, then the once decisive role of the ambassador is clearly diminished.  But this is also to underestimate the role, especially in the modern media world. An accomplished communicator, constantly absorbing and sensitive to a foreign country's mood on a daily basis, is an immense proactive asset for any nation. At its best, it means being able to participate in and influence opinion - having someone to go on the Today programme in the morning, to respond to the newspapers during the day, and to go on Newsnight at the end of the evening.  Above all, though, it means being a nation's dialoguer-in-chief, putting the case not just with the politicians but with the people. Britain's most recent ambassadors in Washington - Christopher Meyer and David Manning - have both been good at this. Many London embassies, including the French and the German, currently have ambassadors who can do it too.  But the Americans, infinitely more important, don't. That absence leaves a vacuum. Ambassador Farish's invisibility meant that most of the British public got its take on American policy from news footage of Bush and Donald Rumsfeld speaking in American ways to American audiences. Or else, since our broadcasters like attention-seekers, they got it hyped up by ideological provocateurs such as Richard Perle or Frank Gaffney.  What explains this deliberate absence from public debate? Is this because American diplomats are now so sealed off that they just don't get it? Or that they have calculated that it is simply not worth the aggravation? Or is it, as one reading of Condoleezza Rice's move to the state department has it, that the Rhett Butler view of the world - "Frankly my dear, I don't give a damn" - now rules across Washington, from Pennsylvania Avenue to Foggy Bottom?  Whatever the explanation, America is wrong not to have a more positive strategy for dialogue with the peoples of other nations, a strategy in which embassies would be bound to play a crucial part. Whatever conclusion one draws about the Iraq war has to include the fact that it constituted an overall failure of US diplomacy. Put the blame where you choose - with America and its allies or with America's opponents, or share it round - but the failure is unresolved business. You only have to look at opinion polls round the world to see that. Anti-Americanism has increased, is increasing and ought to be diminished. But this will not happen without working at it.  There are very few signs anywhere in Europe that Bush's re-election is encouraging an outbreak of pragmatism. Perhaps in Germany, and to some extent in Spain. But not in France, and not in this country either. The readiness of some, happily only a few, to talk down the democratic revolution in Ukraine because it is supported by the US is ultimately more of a problem for those who think this way than for anyone else. But it is indicative of the poisonous nature of the wider problem facing the US, and that poison ought to be drawn.  So we should welcome two recent signs that the American embassy here is beginning to be concerned about the tone of some of the allegations levelled against its country. On November 26, as Naomi Klein described on these pages last Saturday, the London embassy indignantly challenged her claim that the US was fighting a war directed at Iraqi civilians and was "eliminating" witnesses of its policy, notably journalists, doctors and clerics. The same week, David T Johnson, the US charge d'affaires in London, wrote a letter published here on November 27 defending American support for democracy in Ukraine and elsewhere in eastern Europe in the face of an article headlined "US campaign behind the turmoil in Kiev".  Both these responses were overdue in their own right. The one to Klein over Iraq was necessary because of the exceptional seriousness of the charges she is making, while that on Ukraine was a politically important rebuttal of the "my enemy's enemy is my friend" syndrome that has eaten into some anti-American responses to the scenes in Kiev. But the embassy's engagement is also something else: a recognition that the state department believes things have gone too far. Not before time, some might say.  It would be naive to say that the administration's foreign policy problems will be solved merely by international dialogue, still more to imply that the appointment of a top communicator to head each of the US's major embassies would achieve that goal. But these problems will certainly not be resolved without dialogue and better communicators. And unless the US raises its game, it will simply allow others to make the running. A new US ambassador prepared to make Washington's case not just articulately but also respectfully and sensitively would be good for America. But it would be good for Britain, too.