Ignore the rhetoric that the British government would never change policy because of a terrorist attack - of course it would, if there was a coherent policy to be had. Ignore the declarations that we don't try to understand the motives of terrorists - the Foreign Office, Home Office and secret services have researchers whose job is to do just that.
But, setting aside the issue of bowing to terrorism, Britain has little room for manoeuvre in foreign policy. Defined by its closeness to the US, it has a position rather than a policy; the damage is already done.
It is axiomatic that there can be no negotiations with Osama Bin Laden and Ayman al-Zawahiri, who want a new caliphate to replace the western world. The issue is what policies would help dissuade young Muslims such as those who planted the London bombs from joining jihadist groups. The radicalisation of European Muslims is an important part of al-Qaeda's strategy. "Europe is the primary battleground on which the future of global Islam will be decided," says the French expert on political Islam, Gilles Kepel.
Britain has now joined the countries producing suicide bombers. To some extent, this fits a pattern observed by Professor Robert Pape at the University of Chicago, who has shown that most come from countries deemed friendly to the west - such as Egypt, Indonesia, Morocco, Pakistan, Saudi Arabia and Turkey - not "rogue states" condemned by the US as sponsors of terror. President Bush's reiteration that "we must take the fight to the enemy" is rendered meaningless. The priority now is to work with Muslim groups at home, but Europe also needs civil society groups and others to seek an alternative ideology and future for angry young Muslims. The US says that it is trying to promote democracy in the Middle East, but any organisation's credibility will be tainted by US funding, because America is so hated. Time for Europe to step in.
Pakistan is the most potent source of extreme ideology. General Pervez Musharraf has on the one hand tried to rein in extremists, and on the other is using political Islamists to support his party in parliament. It will not be easy to sort out.
The Joint Intelligence Committee said in February 2003 that the threat from al-Qaeda "would be heightened by military action in Iraq". Not that there wasn't a threat earlier - but the invasion of Iraq exacerbated anger, especially among Sunnis. The British government was hoping to reduce military strength in Iraq and increase numbers in Afghanistan, where the UK will lead the international force. Altering the timetable would make no difference to terrorists who oppose the UK presence in both countries. Indeed, if Britain suddenly pulled out, the chances of civil war would increase, potentially destabilising the whole region and creating more al-Qaeda recruits.
Noting that "events that happen far away, in Khartoum or Kandahar, affect us directly", the writer Timothy Garton Ash concludes from the London bombings that "there is no such thing as foreign policy any more". The reverse is also true - events that happen at home reverberate abroad. When I rang an Iraqi friend who had recently been kidnapped for six days, he was equally anxious about me, because he had seen pictures of the London bombings on TV.
If Muslims in Britain are seen as oppressed or victimised, that message will go around the world in an instant.
The banlieues of French cities are full of resentful, underprivileged young men of Algerian and Moroccan descent, ripe to be radicalised: that France did not participate in the Iraq war does not make it immune. Yet, at a critical moment last year, France's Muslims sacrificed a cause to save the lives of two French journalists kidnapped in Iraq. The men who seized Georges Malbrunot and Christian Chesnot said they would kill them if France went ahead with a ban on girls wearing headscarves in school.
French Muslims came out on to the streets to protest against the demand. When he came to London, Malbrunot told how one of his kidnappers had come into the room where they were being held, amazed at what he had just seen on TV. "He said, 'These Muslims in France, they're demonstrating for you.' He was very impressed." Chesnot and Malbrunot believe that dialogue between French Muslims and the government was instrumental in their release. That is why attitudes at home will be so important.
There is one foreign-policy shift that would help. Britain could distance itself a little more from the US over Israel. Not because it would make a material difference - only America has real power in the Middle East. Certainly not to appease Bin Laden, nor even because Palestine is a rallying cry for jihadis in Britain and abroad, but simply because it is a legitimate grievance, a wrong that must, eventually, be put right.
Lindsey Hilsum is international editor of Channel 4 News