Tolerance in multicultural Britain has patently not been broken by the events of September 11th. However, it may be approaching an important point of redefinition. And if there is welcome in Downing Street for a gathering debate about the rights and obligations of citizenship, there might be some apprehension too.
It is already something of a clichΘ that the world was changed completely by the unprecedented terrorist assaults on Washington and New York. As they watched the unfolding horror, people around the globe felt it in their bones. They might not have been able to articulate precisely how or in what way, but many knew an instinctive, terrifying sense that nothing would ever be quite the same again.
One measure of consequence might be the mixed response to Iain Duncan Smith's refusal this week to join Tony Blair and Charles Kennedy in signing a pledge of tolerance towards Islam as part of Islamic Awareness Week.
Mr Duncan Smith insisted he wanted to go beyond the terms of the pledge urging tolerance and condemning racist attacks on people and places of worship, while preserving his antipathy to signing petitions and what MPs call "round-robins" - an approach some campaigners say would make it impossible to establish a cross-party position on any issue.
There was an unholy row during this year's general election campaign when Michael Portillo defied William Hague and led Tories who similarly refused to sign-up to an anti-racist pledge - a decision which had some apoplectic Liberal Democrats virtually blaming the Conservatives for race riots in northern cities and towns. And there was an echo of that this week when the Daily Mirror found the "arrogant Tories" had again failed the "race test", declaring: "It isn't only the battle to bring Osama bin Laden to justice which is so hard. The struggle to convince Muslims that this is not a war against them is proving just as difficult."
Nervous Tories doubtless braced themselves for a deluge of what they would consider "politically correct" denunciation, enmeshing Mr Duncan Smith in familiar controversy of the kind which has so damaged the Conservative Party's electoral standing. By yesterday, however, the Tory leader found himself in the company of the Archbishop of Canterbury and the Chief Rabbi. Dr Carey let it be known that he doesn't sign petitions as a general principle, while Dr Jonathan Sacks was reportedly concerned about the sponsoring Islamic Society of Britain's links with more extreme Islamic groups.
The controversy was playing-out against the backdrop of a growing debate underlying which is a pretty explicit challenge to British Muslims to determine not what their country can do for them, but what they should do for their country. Moreover, the debate is playing across the political spectrum, fuelled by (unverified) reports that as many as six young British Muslims may have died fighting for the Taliban in Afghanistan, assertions that religious faith and the right to support jihad against America come first, and opinion poll evidence that as many as four in 10 British Muslims believe Osama bin Laden justified in his war against the United States.
In the Sunday Times Melanie Phillips sees multiculturalism "imploding under the weight of its own contradictions" and says the attitudes of many British Muslims "should cause the greatest possible alarm that we have a fifth column in our midst". Describing victimhood as inadequate matrix for a multicultural country, the Guardian's Hugo Young said: "The problem is no longer just one of hoisting oppressed communities into membership of a colour blind majority but, it now turns out, of establishing the terms on which a religious minority is prepared to acknowledge prime loyalty to the society in which it lives and works."
No one argued for monocultural uniformity, he continued: "But we're learning that, out of concern for the defence of immigrants, we tiptoe round the values and norms that constitute the obligations that are central to being British, and the policies to serve them."
In a way that Enoch Powell could never have foreseen, the debate about multiculturalism appears to becoming one about loyalty and national allegiance. While civil libertarians and human rights campaigners (not to mention those who have watched Northern Ireland's slow march towards "inclusivity") will see all the potential dangers of stereotyping and Muslim alienation, the view in Whitehall appears to be that this debate reflects the West's discussion with the wider Arab and Muslim world and their need to act against extremists who purport to speak and act in their name.
However, as Mr Blair continues his diplomacy to bolster the coalition abroad, there are dark hints here of just how fragile is the consensus at home.