Of course it was not inevitable. But after 9/11 it was likely, and since Madrid certain, that such attacks would form an occasional but serious part of our Western European lives. London would have had to be extraordinarily fortunate to have avoided an attack completely.
A lot of public and political debate about counter-terrorist measures questioned claims about the scale or reality of the threat. That argument could not have been more tragically resolved. But it doesn't seem likely that the people who mattered ever doubted the threat or what needed to be done.
So we have to face the fact that the terrorists got through despite the careful planning that the police and many locals have been making for just such an event. It wasn't a "terrorist success" because the awful futility of Thursday's action and London's measured response underlines how politically ineffective terrorist action really is. But a debate is bound to open up about how we can reduce the chances of a repeat event.
It is too early to predict the conclusions but it is possible to suggest some of the questions that will be raised.
Perhaps the most straightforward will be the persistent question of "homeland security" and the organisation of the Government's response to terrorism attacks. We need a proper analysis of the emergency response, but the first signs are that the planning structures did their job extraordinarily well. Unless the final analysis shows real weakness, a total shake-up of government to create a homeland security tsar might well do more harm than good. On the other hand, the questions of whether one minister should not work full-time across the whole counter-terrorist agenda will not so quickly go away.
The harder questions will come when we know more about the perpetrators of the outrage.
Good security depends, as ever, on sound intelligence, community support and targeted policing. The security services will be particularly keen to know whether these were led and carried out by foreign nationals or whether British citizens - already involved in international terrorist attacks - are now taking action at home. It's fairly obvious that at the time of 9/11, the security services and the police had better knowledge of foreign terrorists and sympathisers living in Britain than of any home-grown equivalents. The foreign nationals are most likely - though not certain - to be known and most likely to be identified through growing international co-operation and datasharing.
More recent British recruits - who may have developed in response to recent domestic and international events - are a more challenging proposition. Although most estimates suggest a pretty small number even including fringe sympathisers, a lot of effort has been thrown into the new threat by the security service and the police. A fresh assessment of the current strengths and weaknesses of the security response is now unavoidable.
Many in Britain's Muslim community are feeling exposed today. Their worst fears will be realised if the attacks are al-Qa'ida linked with some British extremist involvement. A recent report by the Home Affairs Select Committee highlighted how international terrorism and the response to it had affected community relations in the UK. The British Muslim community is in an unenviable position. Much vilified in the popular press, and often irrationally feared by some otherwise "good liberals", mainstream Muslims have often been left without much support in their daily efforts to resist the extreme views propagated by a tiny minority. Yet their efforts are critical to effective counter-terrorism.
One vehicle for any fresh thinking should be the counter-terrorism Bill that was already promised in the Queen's Speech. Hopes that this would be the first set of anti-terrorist laws not introduced in the wake of an outrage have now been dashed. But the Government should still balance the desire to be seen to act with the need to get a sound framework in place. It may well be we need something akin to French investigating magistrates, or new forms of conspiracy laws, but if so, let us do it properly, building on the lessons that become available from the London outrage.
In a similar vein, the Government should press ahead with existing measures, including its ID card scheme, but it should resist the temptation to sweep all constructive criticism aside in the wake of the bombing. The scheme can be improved and the right changes will make it more likely it can help in the fight against a repeat of Thursday.
The author, a Labour MP, was appointed as chairman of the Commons Home Affairs Committee in 2003Reuse content