IF YOU KNEW what I knew, then you would agree with me. That is what ministers would dearly love to say to justify their new anti-terror laws, but it is the case that they do not dare deploy. The dodgy dossiers about Iraq’s weapons of mass destruction have seen to that. Even so, the more frustrated the Home Secretary and the Prime Minister got with their critics this week the more often that line of argument emerged.

On Wednesday in the Commons, Charles Clarke raised the spectre of a Madrid-style attack being carried out during the election campaign. “Such things are always possibilities in this country, too,” he claimed. “The fact is that terrorists are moving rapidly and it may be necessary to move rapidly to deal with them.” The next day the new Commissioner of the Metropolitan Police, Sir Ian Blair, went farther. “Terrorists have long memories,” he observed, adding, “They understand what happened in Madrid — they know what the impact of that event was on the Spanish electorate.”

Were the authorities trying to tell us something? No, came the vehement, official reply. There is no specific intelligence of an attack during the election. The threat level has not changed. (It has not changed for over a year, I believe. ) So, are Mr Clarke and Sir Ian turning up the temperature in order to win an argument that they are in danger of losing? Absolutely not, I was told. I think I believe them.

Sir Ian is no uncritical friend of the Government. He has joined Michael Howard in arguing for the use of intercept evidence in court. As for Mr Clarke’s warning, it was not in his prepared speech. There was no scripted bloodcurdling rhetoric or prediction of impending doom; it just slipped out. Why, he was asked, did he insist on rushing through Parliament the controversial power to make house arrests when he had no immediate plans to use it? That was when he spoke of Madrid.

It was on his mind, I am told, because he has been preparing to travel to Spain in March for the first anniversary of the attacks that killed almost 200 and changed the result of an election. Both Mr Clarke and Sir Ian are new in their jobs. A risk assessment for a terror attack with contingency plans would surely have been close to the top of their first in-trays.

The other Blair is a friend of José María Aznar, the Spanish Prime Minister who handled the aftermath of the bombings so disastrously, and whose party paid the price. The Prime Minister says that no one would be asking him about civil liberties if, God forbid, an attack did take place. I would be amazed if No 10 has not rehearsed how it would react in the event of a Madrid-style bombing.

So, there is no fresh evidence of a threat, but the danger is understandably at the front of the minds of those pushing for the power to lock people up without trial. It is easy to see why they feel that way. It is easy to see why so many feel that politicians’ fears should not be allowed to dictate the deprivation of any man’s liberty. At the end of the best week of Commons debates since the Iraq war, it is easy to see why writing and talking about politics is so much more comfortable than taking the decisions.

Nick Robinson is political editor of ITV News

nick.robinson@thetimes.co.uk

Times Recommends

• Bank charges hit us for being human
• Sorry, Father, thou still shalt not steal
• The shed where Santa’s failures go to die