We wandered into hypothetical territory, and I was surprised to hear senior officials voicing opinion that "even in times of war" ... "turning-off public communications can be counter-productive."
Given the riots had not yet occurred I can't say how their thinking might have changed, but their reasoning centred around the aftermath of the 7/7 London bombings.
In practice, UK authorities have very little power to restrict internet communications.
It's not that they don't have the legal power - Section 132 of the Communication Act 2003 allows for the Secretary of State to require communications providers to suspend or restrict all or part of their communications network.
But in practice, given the technical complexity of blocking some websites and leaving others visible, and the vastly distributed nature of the internet - utilising resources controlled by thousands of private companies; in practice, the government's powers are pretty blunt.
They could probably shut down the internet in the UK if they wanted, but they would struggle to impose a rapid block on a handful of social networking websites whilst leaving the remainder of the internet - critical to many operations (power generation, healthcare monitoring, etc) - functioning.
Even if it were technically feasible, it's arguable whether Section 132 powers would be sufficient. However, there is always the Civil Contingencies Act 2004, Part 2 of which gives sweeping "emergency" powers to the cabinet to pass emergency laws, side-lining parliament.
Mobile Phone Shut-down
No such technical or legal obstacles exits, however, when it comes to shutting-down or restricting all or part of the UK's mobile or fixed telephone networks. This can be done under Section 132 powers, and I'm told there has been a great deal of debate into if or how these powers should be used in the event of a terrorist attack on the UK.
There are three reasons why the government might want to restrict access to mobile phone networks:
- Preventing "ordinary" calls would free-up channels (bandwidth) for emergency calls. This is a somewhat over-simplified argument banded around by people who don't fully understand how the networks operate - emergency calls already get priority on networks, booting-off existing calls if necessary. But the thinking is calls to/from 999 and equipment attached to the public network used by emergency responders would have more capacity.
- It would stop terrorists communicating to plan their getaway, or further atrocities
- It would stop the remote detonation of any further devices equipped with mobile phone detonators.
By chance, a group of senior doctors were convened at the headquarters of the British Medical Association close to Tavistock Square. These doctors had access to mobile phones, but no official emergency communications devices.
The underground bombs damaged the cables used to connect emergency phones, leaving the driver of the Aldgate train to alert authorities using his mobile phone.
There being no official system of alerting emergency responders across the capital to an emergency on the London Underground, mobile phones were used to disseminate news of the emergency, thereby aiding in the relief effort.
Clearly public communications of any type (mobile phones, internet telephony, social networks, etc) can be abused by those wishing to harm society. But in a democracy they are used, overwhelmingly, as a force for good.