They could make out the words DASH FOR FREEDOM on her front and BREAK FREE on her back. Her identity card hung 10cms below her navel on a gold chain. Two police motorcyclists followed her for 200 yards and helped officials manhandle her off the track.

Most of those who saw the incident on their PDAs replayed it several times in the next hour. They also looked at the best of more than ten thousand amateur clips shot by spectators on their PDAs.

Computer-enhanced pictures revealed the provocatively positioned words clearly, along with the shaven head, stage make-up and naked body glistening in the rain. The marathon winner's Olympic record triumph was eclipsed. The world wanted to know who had stolen the show.

The identity card, so prominently displayed, was false. At 17.07, a police bulletin was issued: “The Stratford Stadium streaker has remained silent. Our biometers have checked her finger, lip, earlobe and DNA prints, all of which are on the card she was wearing when arrested. We have been unable to confirm the signature or voice-print. The card is a good forgery but not good enough to fool our systems.

We have found the ex-Army camouflage rain cape which she discarded as she leapt the barrier onto the course.

A further bulletin will be issued as soon as we have a definite ID. Meanwhile, our computers are synthesising a polyscope from the thousands of videos distributed on the Internet. We are also sifting the calls to the Olympic security call centre, most of which appear to be part of a distributed denial-of-service attack. Someone may have recognised her and made a genuine call.”

Just as the IOC President started his closing address to the athletes, the spectators' eyes turned again to their PDAs.

“The Public Order and Transport Police have identified the Stratford Stadium Streaker. She is Jane Doe, who changed her name from Mary Smith seven years ago. A search of the databases associated with the national ID card system using her biometrics showed only one match for all the measurements. Her last quinquennial renewal photograph is attached to this bulletin.

We have also identified many of her blood relations, fellow students, work colleagues and sports team-mates whom we will be interviewing shortly.”

The Stratford Stadium Streaker story was a global sensation, not least because sympathisers with her cause stoked the flames of publicity on the Internet. They bypassed attempted censorship as easily as Jane had slipped past the course barriers.

Jane was a member of Hereward's Heroes, a clandestine network of freedom fighters linked through cyberspace. Each 'hero' operated alone and was unknown to the others until revealed by a public exploit.

Some were hackers; all were conversant with computer security and insecurity. They took their name from Hereward the Wake, who led the English rebels against the tyrannical William the Conqueror, compiler of the national database known as the Domesday Book.

Mary Smith became Jane Doe just as the UK started to issue identity cards. As a student reading sports science, she specialised in information and communications technologies and coaching - and still found time for the modern pentathlon.

Her projects focused on the bane of all sports, cheating: psychology, motivation, techniques, media manipulation, networking and detection. She worked for a global IT company on the security of some of the computer systems for the Beijing Olympics and later taught systems security in an Indian university. She continued to coach amateur teams and kept fit.

Travel to sporting events abroad required a UK passport and ID card. The same 'documents' were recognised by international and national sports federations and were linked to the global databases of athletes' performance and medical history - used e.g. for anti-doping measures and spotting 'talented DNA'. So Jane had her UK ID card almost as soon as they were issued.

She added further biometrics at her first quinquennial renewal and pulled off a full copy of her biography from the ID network system at the same time. It was full of errors and omissions, particularly with respect to her foreign travel, but she did not bother to correct them.

Some information about other Jane Does had, to her amusement, contaminated her files from America, although remarkably little seemed to be known about any of them by the US authorities except that each appeared to be English.

Her professional and sporting activities took Jane abroad and opened her eyes particularly to the different relationships between people and governments. She got drawn into the 'security versus liberty' debate, spoke out at an international professional conference and lost her job: her employer in Beijing was bidding for a 2016 Olympics contract.

But a Hereward Hero had heard her and became her mentor in asymmetrical warfare: wait for the right time; stay hidden until you strike; hit the enemy where it hurts - in his dignity; and get the public with you, not against you.

The public loved the Stratford Stadium Streaker for showing up an overbearing government and its decade-old Committee for Public Safety. Identity cards had crept from a technical aid to security to a state-imposed burden in the duration of two parliaments.

In 2008, the UK government started the Now We Are Grown Up scheme, issuing ID cards to all children in a prize-giving ceremony as they leave primary school. Their records were linked to their legal and biological parents' records to facilitate e.g. preventing epidemics and managing truancy. All children in State secondary schools were required to carry their cards at all times, an effective curb on anti-social behaviour.

Recognising that the chip, not the plastic card, was the critical element, the updating Act of 2009 allowed the chip to be carried in a PDA, provided that it met the qualifying standards. Most people chose to carry a single device, which combined ID card, video camera, telephone, TV screen, personal computer, internet access, navigator and keys.

They would respond only to their owners and set off an alarm if separated by too great a distance. These PDAs could of course be tracked, but accessory shops sold 'Faraday Cages' in which to conceal them. For truanting teenagers, these were a 'must have'.

The invasion by millions of foreigners for the 2012 games and the precursor cultural festival forced the UK government to require everyone to carry identification at any Olympic or other designated venue and on public transport serving such venues.

This approach was tested on football fans during the 2010/11 season. It was proved that security video cameras could home in on carriers of individual PDAs and on seats sold to specific fans who had switched their PDAs off.

Since the PDAs held the tickets and ushered the holders to their seats, it was impossible to get into the ground without one. However, since these were available free with a subscription for message carriage or a contract with an advertising channel, everybody could afford one.

The Stratford Stadium Streaker showed that ID cards were not needed for identification. The police used her biometrics to find her biography in the data bases within an hour. Since a biometer is necessary to measure someone and link her to her ID card, a national card-based system requires several million biometers in shops, police stations, buses, cash dispensers, staff entrances, personal computers and, of course, card issuing offices.

These last process a million new and replacement cards a year, linking the data subject to the databases containing the biographical data. (Nobody now brings a utility bill, countersigned form or other document as 'proof'.)

All the links are with and between electronic systems, which have captured the subject's biography from conception onward. At least one has her electronic signature so she can sign electronic documents. With a co-operative data subject pointing out where to look, inter-communication takes only seconds.

By 2012, biometers had dropped in price below the cost of ID cards. Additions and replacements to the national stock of biometers were running at less than the replacement rate for cards and at lower unit cost.

Most PDAs could identify a stranger from his voice by transmitting a standard spoken greeting to a national voice recognition centre. Normally, however, they exchanged IDs with the other party's PDA, quickly establishing when they last met and what brought them together then, since both had the occasion logged in their diaries.

In 2013, the ST3 Act (STratford STadium STreaker Act), as it came to be known, abolished ID cards. Introducing the Bill in the Commons, the Home Secretary said: “If only we had known in 2004 what is now so obvious to us, we could have saved the taxpayers £5 billion....”