Here's what the future Mayor Johnson wrote in The Spectator shortly after the bomblings of 7 July 2005:

The Islamicists last week horribly and irrefutably asserted the supreme importance of [their] faith, overriding all worldly considerations, and it will take a huge effort of courage and skill to win round the many thousands of British Muslims who are in a similar state of alienation, and to make them see that their faith must be compatible with British values and with loyalty to Britain. That means disposing of the first taboo, and accepting that the problem is Islam. Islam is the problem. To any non-Muslim reader of the Koran, Islamophobia - fear of Islam - seems a natural reaction, and, indeed, exactly what that text is intended to provoke. Judged purely on its scripture - to say nothing of what is preached in the mosques - it is the most viciously sectarian of all religions in its heartlessness towards unbelievers.... It is time that we started to insist that the Muslim Council of Great Britain, and all the preachers in all the mosques, extremist or moderate, began to acculturate themselves more closely to what we think of as British values.

Emotions ran high after that cruel atrocity in Central London, so perhaps allowances should be made. Also, if you read the whole article, you'll see that Boris's argument is more nuanced than this extract might make it appear. Even so, his claim that Islam is intrinsically an obstacle to Muslim loyalty to Britain seemed pretty unequivocal. Compare it with what he said during a Politics Show debate last April as Mayoral election polling day approached:

The problem is people who wrench out of context quotes from the holy book of Islam, the Koran, and use it to inspire evil in men's hearts. That is a fact that few serious people would deny and we need to tackle the extremists.

So three years after 7/7 Boris no longer seemed prepared to say that "Islam is the problem" only that a minority of Muslims who deliberately misinterpret its scripture are. And now this, uttered at the East London Mosque last Friday:

I urge people, particularly during Ramadan, to find out more about Islam, increase your understanding and learning, even fast for a day with your Muslim neighbour and break your fast at the local mosque. I would be very surprised if you didn't find that you share more in common than you thought.

This has excited much comment, most penetratingly at Harry's Place where (via Conservative Home) some rather unBritish connections of the mosque's imam are documented at length. My interest here, though, is in Boris's intriguing journey from an anti-Islam, pro-"Britishness" position where he called for Muslims to align their faith with "British values" to one where he urges everyone who's not a Muslim to sample an Islamic lifestyle.

Perhaps the answer lies in something else he said in Whitechapel last week:

Whether it's in theatre, comedy, sports, music or politics, Muslims are challenging the traditional stereotypes and showing that they are, and want to be, a part of the mainstream community...Muslims are at the heart of every aspect of society. Their contribution is something that all Londoners benefit from. Muslim police officers, doctors, scientists and teachers are an essential part of the fabric of London. Islamic finance is contributing to the economy by changing the way Londoners invest, save, borrow and spend. There are valuable lessons that people of all backgrounds can learn from Islam such as the importance of community spirit, family ties, compassion and helping those less fortunate, all of which lie at the heart of the teachings of Ramadan.

It really does appear that "Islam is the problem" no more - quite a conversion. Is it because Boris believes that his call for British Muslims to embrace "British values" has been heeded in the four years since he made it, or might other factors be at play?