Welcome to Fortress Britain, a fortress that will keep people in as well as out. Welcome to a state that requires you to answer 53 questions before you're allowed to take a day trip to Calais. Welcome to a country where you will be stopped, scanned and searched at any of 250 railways stations, filmed at every turn, barked at by a police force whose behaviour has given rise to a doubling in complaints concerning abuse and assaults.

Three years ago, this would have seemed hysterical and Home Office ministers would have been writing letters of complaint. But it is a measure of how fast and how far things have gone that it does nothing more than describe the facts as announced last week.

We now accept with apparent equanimity that the state has the right to demand to know, among other things, how your ticket has been paid for, the billing address of any card used, your travel itinerary and route, your email address, details of whether your travel arrangements are flexible, the history of changes to your travel plans plus any biographical information the state deems to be of interest or anything the ticket agent considers to be of interest.

There is no end to Whitehall's information binge. The krill of personal data is being scooped up in ever-increasing quantities by a state that harbours a truly bewildering fear of the free, private and self-determined individual, who may want to take himself off to Paris without someone at home knowing his movements or his credit card number.

Combined with the ID card information, which comes on stream in a few years' time, the new travel data means there will be very little the state won't be able to find out about you. The information will be sifted for patterns of travel and expenditure. Conclusions will be drawn from missed planes, visits extended, illness and all the accidents of life, and because this is a government database, there will be huge numbers of mistakes that will lead to suspicion and action being taken against innocent people.

Those failing to provide satisfactory answers will not be allowed to travel and then it will come to us with a leaden regret that we have in practice entered the era of the exit visa, a time when we must ask permission from a security bureaucrat who insists on further and better particulars in the biographical section of the form. Ten, 15 or more years on, we will be resigned to the idea that the state decides whether we travel or not.

Who pays for the £1.2bn cost over the next decade? You will, with additional charges made by your travel agent and in a new travel tax designed to recoup the cost of the data collection. But much of the money will go to Raytheon Systems, the US company that developed the cruise missile and which, no coincidence, has embedded itself in Labour's information project by supporting security research at the party's favourite think-tank, the Institute for Public Policy Research.

The odour that arises from the Home Office contract with Raytheon is as nothing compared to that created last week when the Home Secretary and Prime Minister used the announcement of the 'E-borders' scheme as well as increased security at shopping centres, airports and railway stations to create an atmosphere that would push MPs to double the time a terrorist suspect can be held without trial. It also helped to divert attention from the mess in another Home Office database concerning upwards of 10,000 security guards who may be illegal immigrants.

On detention without trial, no new arguments have been produced by Gordon Brown. He won't say how many days he wants and he won't answer David Davis, the shadow Home Secretary, who points out that all the necessary powers to keep people in jail after a large-scale attack are provided in the Civil Contingencies Act 2004.

To this, Brown replies that declaring a state of emergency would give terrorists 'the oxygen of publicity'. How does he square this absurd statement with the high alert being sounded by police, politicians and spies over the past two weeks, which has given the greatest possible publicity to the power of the Muslim extremists to change our lives?

The truth is that while his government limps, heaves and splutters with an incompetence only matched by its unearthly sense of entitlement, the Prime Minister has become fixated with this issue as though it were a virility test. So his chief Security Minister, Lord West of Spithead, who had voiced his doubts about raising detention without trial on Radio 4, was hauled into Number 10 to have his thoughts rearranged. Less than an hour later, he appeared like an off-duty ballroom dancing champion and adjusted his conviction as though it was no more than a troublesome knot in his very plump, very yellow silk tie. He will not resign of course. What is a mere principle placed against his recent elevation to the Lords and the thrilling proximity to power?

How have we allowed this rolling putsch against our freedom? Where are the principled voices from left and right, the outrage of playwrights and novelists, the sit-ins, the marches, the swelling public anger? We have become a nation that tolerates a diabetic patient collapsed in a coma being tasered by police, the jailing of a silly young woman for writing her jihadist fantasies in verse and an illegal killing by police that was prosecuted under health and safety laws.

Is it simply that the fear of terrorism has stunned us? The threat is genuine and the government is right to step up some security measures, but let us put it into perspective by reminding ourselves that in the period since 7/7, about 6,000 people have been killed on our roads. And let's not forget the bombings, assassinations, sieges, machine-gunning of restaurants and slaughter that occurred on mainland Britain during the IRA campaign. We survived these without giving up our freedoms .

Or is there some greater as yet undefined malaise that allows a sinister American corporation to infiltrate the fabric of government and supply a system that will monitor everyone going abroad? I cannot say, but I do know that an awful lot depends on the 40 or so Labour MPs needed to defeat Brown's proposals on pre-trial detention. They should be given every encouragement to defy the whips on the vote, which is expected within the next fortnight

It is important that the press has moved to the side of liberty. The Daily Mail, which I wrongly excluded from the roll of honour last week, attacked Jacqui Smith for 'her utter contempt for privacy' and warned against the travel delays and inevitable failure of another expensive government database. And Timothy Garton Ash, who has so far stayed above the fray, wrote in the Guardian last week that 'we have probably diminished our own security by overreacting, alienating some who might not otherwise have been alienated'. Labour MPs should listen to these voices.

The Prime Minister is found of quoting Churchill, so I will again: 'If you will not fight for the right when you can easily win without bloodshed, if you will not fight when your victory will be sure and not costly, you may come to the moment when you will have to fight with all the odds against you and only precarious chance for survival.'

henry.porter@observer.co.uk