[Editor's note: I mentioned the arrest of technology editor David Mery in my recent Guardian column on Prism; he wrote in to correct some details and explain the astounding circumstances of how Britain's absurd war on terror caught him in its mesh for the crime of wearing a coat in the summer -CD]
I was observed directly when I entered Southwark tube station and then on CCTV. All the time it was by Met police officers. To my knowledge no computer algorithms were involved. In Naked Citizen, Patrick Hafner mixes the interview he did with me and some CCTV recognition algorithms, but the two are not directly related. The Met police officers at the entrance of the station were those who found my behaviour suspicious and decided initially to stop and search me under s44 of the Terrorism Act.
Who exactly took the decision to arrest me and the choice of legislation is less clear, as it appears that initially officers wanted to arrest me under the Terrorism Act but were overruled and decided on Public Nuisance (which can still carry a life sentence).
The Met and IPCC investigation files are still retained (until 2015 and 2014) but my police national computer record was deleted as well as my fingerprints and DNA, and I eventually also got the photographs back. The short version of the whole story is here.
That I let a tube train pass by without boarding it is the only important dispute in the police version of events and mine. That's the police version. Mine is that I tried to board the first train that arrived, but was then stopped by the police.
The Metropolitan Police never got the CCTV footage (the officer in charge was told to do so by his superior but never did and is the main reason he got some warning), Transport for London retained it only for 14 days and I asked for it too late.
What is more relevant in the context of your story is that unrelated intelligence on file that was linked to work connections was a input in the decision to arrest me.
As I wrote: 'The officer explains what made them change their mind and arrest me instead of releasing me. It was because of my connection with my employer. Apparently, on August 4th, 2004 there was a firearms incident at the company where I work. (The next day I find out that there had indeed been a hoax call the previous year, apparently from a temp worker claiming there was an armed intruder in one of the buildings.)
Also that some staff had been seen taking photographs of trains at the tube station with a camera phone. (Most of my colleagues do have camera phones – also on 2nd June, as part of a team building exercise, new graduates were supposed to photograph landmarks and try to get a picture of themselves with a policeman.)'
As you probably know, and as it no longer exist there's no issue in now naming my then employer, it was Symbian. As the provider of the OS for the then majority of smartphone, Symbian obviously must have had some relationship with GCHQ at least for export control regulation of encryption.
Your conclusion about my experience: 'Once a computer ascribes suspiciousness to someone, everything else in that person's life becomes sinister and inexplicable.' remains entirely valid and is why I fought so hard to expunge my records and help fight for other innocents as well.
I've included a short list of examples of why this suspiciousness may make one's like sinister (in the context of the NDNAD) here.