Adding yet another facet to our surveillance society, the government has been quietly running a creepy and intrusive experiment in tracking our movements using mobile phone data as an alternative to traditional census data collection methods. This opportunistic data grab offers a deeply disturbing glimpse into a not-too-distant future where the tracking device in your pocket is routinely used to amass detailed data about your behaviour, privacy be damned. The use of mobile phone data in this way not only raises some important security concerns, but also risks infringing upon our civil liberties. The Office of National Statistics has promised an evaluation of privacy impacts before rolling it out further, but this is not a government that prioritises the privacy of its citizens. The ONS revealed details of how it used anonymised mobile phone records of Vodafone customers in three London boroughs to track their daily commutes over a four-week period in 2016. The stats body is now asking for feedback. How does it work? While switched on, your mobile phone constantly connects to nearby masts that, via a process of triangulation, enables the approximate location to be calculated and stored. This information has long been used by law enforcement agencies during criminal investigations. Before diving into why using mobile phone data in this way is the tip of a particularly worrisome iceberg, there are two exacerbating factors that makes this even more problematic. First, this is the same government that introduced the "draconian" Investigatory Powers Act, or Snoopers' Charter, that empowers it to bulk hack its citizens, collect their browsing histories and cross-reference massive databases. Given that they also want to be able to read your Whatsapp messages, is this really a government you can trust to monitor your physical movements? Secondly, this administration has made an ideology of austerity. To put it bluntly, this is a cost-cutting exercise. Buying third-party data is cheaper than collecting it yourself, and they will aim to extract as much value as possible from their purchase by expanding its use as far as possible. Analysis of commuting patterns is just the start, as there is much to learn from our daily movements. If that were to happen, independent assessment of any anonymisation methods used to ensure that no personally identifiable information could be extracted from the data is an absolute must. The public audits of encryption and white-hat stress-testing would be the obvious model to follow. Anonymization of mobile phone records is far from an easy feat and there have been examples where individuals have been identified from supposedly anonymized data, such as the notorious release of AOL search data in 2006 or the search history of three million Germans earlier this year. All the more reason to require the aggregation algorithms be put to the test transparently. The government would also need to convince us that it could secure its new treasure trove of data. It's the era of the massive data breach, with what feels like a new hack every other week. All this data in one place would be very attractive to cybercriminals emboldened by recent successes, such as the Equifax hack of 143 million consumers' records. Even as it stands, it's hard to be comfortable with the fact that Vodafone customers would have been unaware that they have been tracked in this way, as the sale of their anonymised data is permitted under the terms of their contracts. This brings us to the issue of choice. There will be many simply not comfortable with such intrusive tracking, for whom there should be an opt-out. Yet this appears unlikely, if the current mandatory completion of the census is anything to go by. It doesn't feel very democratic that there's been no public debate about whether we want to live in a society where our every movement is tracked and stored in databases. What's more, this attack on our privacy is also coming from the tech giants, Google, Apple, Facebook et al, who gather terrifyingly accurate records of our movements, unless we dig into our settings and opt out. Check Google Maps Timeline for a chilling example of what this looks like. The government has finally woken up to this huge potential for data collection on the British public. It isn't a huge leap to imagine that once they have sucked dry the mobile phone networks, they will turn to Google and co and legislate their way into getting their hands on yet more data. At that point, individual privacy truly would be dead.