When the writer of Prime Suspect, Peter Berry, started a new TV drama set in a "near future" Britain that's become a security state, he didn't expect current events to overtake his imagined plot.
It might have been 20 years ago when I noticed two men on the platform at Euston station. They were businessmen, heavy overcoats, bound for Manchester. The larger of the two picked a thread from the overcoat of the smaller man, as if he owned him.
The smaller man looked powerless and I knew that it was this relationship I wanted to explore in The Last Enemy: the power of the state over the individual; the power of the official who stops you in the street and demands to see your papers; to check your data, your private history.
Yet when I finally sat down to start the script, four years ago, the contrast in pace couldn't have been more pronounced.
UK has more CCTV cameras per head than any other country
A trick that script writers use to help focus their story is to think up the slogan for the movie poster. As I embarked on the first draft in 2005 there was a debate getting underway about ID cards and whether or not we were sleepwalking into a surveillance society.
I set the story in the future at a time when ID cards were compulsory and we were all under greater surveillance after a terrorist attack in the UK. I didn't want to write science fiction; I wanted reality set just around the corner.
So writ large across my poster was: "The Future is Closer than You Think". It was a slogan that turned out to be horribly true; I delivered the script a month before the London tube bombings.
After 7 July, anti-terrorist legislation was brought in with breathtaking speed: ID cards linked to a central database, the dilution of habeas corpus, constraints on the rights of freedom of speech and of freedom of assembly; reality was threatening to overtake my "futuristic" story.
Taken for granted
Technology was also rapidly changing: in an early script I had CCTV cameras that could not only listen but lip-read. I edited this out because it was thought too fanciful, yet such cameras and software are now installed in our cities.
But I didn't want the "villain" of the piece to be power-mad politicians or an intelligence service hell bent on curtailing our civil rights. That's not a realistic picture.
The 7 July attacks show "the individual has never been so dangerous"
We are all responsible for the state in which we live. I wanted to write about us, the sleepwalkers. My central character, Stephen Ezard, returns to Britain having spent some years in China, and this gives him a clear perspective of just how much his homeland has changed.
Britain is no longer the country he had always taken for granted; the tolerant liberal democracy that is our default setting. Our perceptions have perhaps become dulled by living here.
Ezard discovers a country that has come under increasing terrorist attack and has now has a high level of surveillance with more aggressive policing.
Confusion over cards
Five million CCTV cameras, more cameras than any other country and a centralised database of all your personal details linked to an ID card.
It's not the Britain he knew a few years ago, but to those who live here it doesn't feel so different because the changes have been gradual.
We have an intelligence service who work incredibly hard and are passionate about saving our lives
Terrorist attacks have shown that the individual has never been potentially so dangerous and at the heart of the story is the question of how much information the state should know about us and in what form. There now seems to be confusion over ID cards: will it be a voluntary system, and if so, what purpose might that serve?
Or will cards become compulsory through stealth - a necessity for travel, banking, employment, or to access health and welfare?
A comparison is often made with ID cards on the Continent, yet they are nothing like the UK ID card because they hold far less information.
Mass of information
Plans for the UK ID card are that it will be linked to the National Identity Register, a centralised data bank that can hold up to 50 categories of personal information: current and any subsequent places of residence, fingerprint details and other biometric information, national insurance number and driving licence details. (See internet links, above right, for a full list.)
Yet it's not simply a case of pointing a disapproving finger at the "tentacles" of the state. There's a laziness in the constant expressions of "they are watching us". In fact we have an intelligence service who work incredibly hard and are passionate about saving our lives. But if you let police make the laws, quite logically you end up with a police state.
First ID cards to foreign nationals this year
From 2010, all passport applicants will be issued with ID cards
MPs will vote on whether to make them compulsory
Ministers say ID cards boost national security, tackle identity fraud, prevent illegal working and improve border controls
Critics say they are an infringement of civil liberties and a waste of money
They will contain a photo, name, address, gender and date of birth. A microchip will hold biometric information
And there's a similar laziness in the belief it's only the guilty who have something to lose; the innocent have nothing to hide. To many the perils of a surveillance society seem abstract, a load of "what ifs" that will never have much bearing on most of our lives.
Yet the innocent do have something to hide - their privacy, and that is linked to dignity. The innocent will have to prove every day that they are innocent by what is on their card.
The purpose of The Last Enemy is of course to entertain; hopefully at the end of five-and-a-half hours there will also be a resonance.
Peter Berry's new drama series The Last Enemy is on BBC 1 at 2100GMT on Sundays from 17 February. The programme was made by Box TV.
Below is a selection of your comments.
"Yet the innocent do have something to hide - their privacy, and that is linked to dignity." That's it? I care more about stopping people being robbed and attacked on the streets than about whether some anonymous bureaucrat can check my driver's license record or my health records. In fact I feel no sense of a loss of a dignity at all in those kind of checks, it's when I'm a victim of crime that I feel a loss of dignity. The dilution of habeas corpus/freedom of speech etc is an entirely different matter of course.
ID cards will be linked to a database, and this, not doubt, will be computer-based. Computers and software can only do what they are told to do - by humans. And humans are prone to mistakes. It wouldn't even take sabotage, just error, for the system to wrongly accuse someone of a crime, or have them confused with someone who really was a criminal. The computer would say it was them. And who would believe they were innocent? There will be even worse miscarriages of justice as a result.
I think heightened security measures only make people more jittery. There was a story this week that a guy got arrested by armed police because someone thought his MP3 player was a gun an contacted police. All these "report terrorism if you suspect it" posters do little to reassure people in my opinion, and are more likely to divide society and create a generation of people who panic over the slightest thing.
John, London, UK
I refuse to believe that the vast increase of money we now spend on national security compared to pre-9/11 has saved more lives than if it had instead been diverted into safer roads, domestic abuse prevention programmes and closer monitoring of repeat offenders when they're released. These days you can be watched along all major A and M category roads, the whole rail network and all airports, from the start of your journey to the end. And for what purpose? To prove after a terrorist event where the bombers started their journey from, or are the CCTV systems used for far more than just that? I do not understand why we need so many CCTV cameras, I've yet to see a concrete justification for them.
Alex, Birmingham, UK
Alex, are you suggesting that we spend no more money or resources on terrorism? Are you not aware that the risk has actually grown since 9/11, that this has galvanised elements of society? The security services have no doubt prevented many a disaster from occurring which are unpublicised for security and operational reasons that we don't give them credit for. Even after a crime or disaster has occurred these CCTV and security resources allow the accomplices, organisations etc to be identified which can lead to prevention of future attacks and dismantling of terrorist organisations.