Can you guess who wrote the following words in the Observer in May 2007? "We cannot bully people into feeling British: we have to inspire them . . . by using the word 'Islamist' to describe the threat, we actually help do the terrorist ideologues' work for them . . . Integration has to be about more than immigrant communities . . . It has to be about 'us', too . . . integration is a two-way street."

Were you able to identify the multiculti, muesli-eating sandal-wearer? I'll give you a clue. The author of that rather nuanced article delivered a speech in Munich on 5 February, in which he declared: "We need to be absolutely clear on where the origins of these terrorist attacks lie - and that is the existence of an ideology, 'Islamist extremism' . . . Under the doctrine of state multiculturalism, we have encouraged different cultures to live separate lives, apart from each other and the mainstream . . . we need a lot less of the passive tolerance of recent years and much more active, muscular liberalism."

Yes, the speaker was David Cameron. So how did the Muslim-hugging leader of the opposition of May 2007 become the "muscular liberal" Prime Minister of February 2011?

There are two explanations for the shift in tone and message. The first is that Michael Gove has won. The Education Secretary and close ally of the PM has long argued that the threat from militant Islam is akin to Nazism and condemned the west's "policy of appeasement" in his fear-mongering 2006 book, Celsius 7/7. Cameron has, in a sense, been captured by Gove and his fellow neoconservatives and securocrats within the coalition cabinet - George Osborne, Liam Fox and Theresa May.

Their victory is a defeat for the more moderate cabinet Conservatives Ken Clarke and Sayeeda Warsi, as well as the Liberal Democrat ministers Nick Clegg and Chris Huhne.

Dog-whistling

The second explanation relates to wider events. Growth has gone negative. Spending cuts are unpopular. The "big society" is in crisis. What better way for Cameron to re-establish his right-wing credentials - and divert attention - than with an attack on multiculturalism?

“Every single Conservative would have loved this," says Tim Montgomerie, editor of the ConservativeHome website, who complained on this page last week that the government should adopt more "mainstream" Conservative positions. "This speech has happened at an appropriate time in terms of bolstering his position in his party."

But the speech was muddled and superficial. The Prime Minister did not deign to define his straw men - multiculturalism and Islamism. What exactly is a "state doctrine of multi­culturalism"? Does it include a commitment to faith schools - denounced by critics as "divisive" but endorsed by Cameron's Conservatives? If these dastardly and deadly "Islamists" pose such a threat to "our way of life", why does the Prime Minister describe himself as the "strongest possible advocate" of Islamist-ruled Turkey's accession to the EU?

Far worse, however, were the timing and the location of Cameron's comments. Was it wise to lecture British Muslims from a foreign land on the same day - Saturday 5 February - as some of those Muslims were being harassed, intimidated and threatened by the far-right thugs of the English Defence League (EDL) on the streets of Luton ? "The timing was a coincidence," insists an adviser who worked with Cameron on his speech. Perhaps. But the fact is that the EDL leader, "Tommy Robinson", delighted in informing his fellow demonstrators in Luton that the Prime Minister was "now saying what we're saying. He knows his base."

And why give a speech about British Muslims in Germany, where anti-Islamic sentiment is at an all-time high? The recent book by the German banker Thilo Sarrazin, which argues that fast-breeding and ill-educated Muslim immigrants are "dumbing down" Germany, sold over a million copies there in 2010.

Cameron's dog-whistling cynicism should come as no surprise. But where does Labour stand on all this? Will Ed Miliband speak up for multicultural Britain; for integration over assimilation; for the virtues of diversity, tolerance and mutual respect? It is worth remembering that Tony Blair gave a speech similar to Cameron's in December 2006. Meanwhile, Gordon Brown's most memorable contribution to the debate over identity consists of five words: "British jobs for British workers".

On the day of Cameron's Munich speech, the shadow justice secretary, Sadiq Khan, who happens to be Muslim, accused the Prime Minister of "writing propaganda for the EDL". He came under fire from the Tories and the right-wing press but there was only silence from the rest of the Labour front bench. Yvette Cooper and Douglas Alexander appeared on the BBC and Sky News the next day and pointedly distanced themselves from Khan. "It is for Sadiq to explain the context in which he made those remarks," said Alexander on BBC1.

Hung out to dry

One senior Labour MP I spoke to said that Khan, gleefully described as isolated by the Daily Mail, was "hung out to dry", adding: "The members of Ed Miliband's 'new generation' just don't get race. Those who battled with the National Front [in the 1970s] have long since retired from front-bench politics."

A shadow minister agrees: "It's a blind spot for the leadership." The likes of Cooper (Normanton, Pontefract and Castleford) and Alexander (Paisley and Renfrewshire South) represent seats with small ethnic-minority populations. The only shadow cabinet minister publicly to back Khan was the veteran anti-apartheid campaigner Peter Hain, who tweeted his support. But I'm told that when the subject was raised at a shadow cabinet meeting on 8 February, Miliband said "there wasn't time". The discussion turned to whether or not to give prisoners the right to vote.

Can Labour in opposition develop a political narrative that reflects and promotes the reality of multicultural Britain, while addressing the genuine if misguided concerns of some "white working-class" core voters as well as wider anxiety about the radicalisation of a minority of young British Muslims? Or will shadow ministers continue to cower at the feet of the Daily Mail? Miliband et al should think long and hard about everything that was wrong about Cameron's simplistic and inflammatory speech - and how best to respond to it.