There is only one reported case of a UK network being closed by police. During the 7/7 London suicide bombings, O2 phone masts in a 1km square area around Aldgate tube station were disconnected for a number of hours.
Police have an emergency power to order masts to be put out of action known as MTPAS – Mobile Telecommunication Privileged Access Scheme. The move has to be approved by Gold Command, by the officers in highest authority during a major incident, and is designed to restrict all but emergency service phones with registered sim cards from making calls. But a shutdown can have dangerous knock-on effects. Short says that phones within the Aldgate zone automatically sought a signal from live masts outside it, overloading them and causing a network failure that rippled out "like a whirlpool".
On the day, other networks were simply overloaded as Londoners sought reassurance and information. Vodafone alone experienced a 250% increase in call volumes
MTPAS is the GSM-land equivalent of the old fixed phone Telephone Preference Scheme (not to be confused with the new one that blocks cold-callers), which permitted The Authorities to turn off between 1% and 90% of phone lines in order to let official traffic through. As far as I know, the Met never asked for it and it was City of London Police who initiated it without asking the Met or anyone else, and in fact O2 UK's network had been keeping up with demand up to that point, before the closure caused the cascade failure Short describes.
The significance of O2 is that it used to be "Surf the Net, Surf the BT Cellnet" and some residual gaullist/spook reflex in the government tried to keep official phones on what was then one of two British-owned networks.
Anyway, this weekend seems to have the theme "The Intersection of Charlie Stross and the August 2011 Riots". Charlie's talk at USENIX is sensibly sceptical about some tech dreams as they apply to networking.
This leaves aside a third model, that of peer to peer mesh networks with no actual cellcos as such – just lots of folks with cheap routers. I’m going to provisionally assume that this one is hopelessly utopian, a GNU vision of telecommunications that can’t actually work on a large scale because the routing topology of such a network is going to be nightmarish unless there are some fat fibre optic cables somewhere in the picture. It’s kind of a shame – I’d love to see a future where no corporate behemoths have a choke hold on the internet – but humans aren’t evenly distributed geographically.
Especially as the theoretical maximum bandwidth of one fibre is about the same as the entire radio spectrum. And the point about routing table size and complexity is a very good one, especially as it's assumed that the routers aren't CRS-1s but rather Linksys fifty quidders or mobile phones.
However, one thing the liberation technologists should take away from the riots is that you shouldn't get hung up on bandwidth. It's great to be able to post the photos on Flickr, but it's more useful to have your own secure voice and messaging. When the Egyptian government relented on its GSM cut-off, the Egyptian Twitter feeds lit up with calls for more people to this or that exit of Tahrir Square or medical supplies to the clinic or (and I remember this) that a lost child was waiting at the press tent.
It was what NANOG users would call operational content. There was of course no need whatsoever for it to go via a Bay Area website - all Twitter provided was the one-to-many element, very important, and the publicity on the Web. The latter is a nice-to-have feature, the former, critical. Text, or even voice, is not a high bandwidth application and doesn't necessarily need access to the global Internet.
So yes - perhaps there is in fact quite a bit of angular momentum to be had in a mobile mesh-WLAN client as an instrument of democracy, as long as you're willing to accept that it's not the sort of thing that can be exclusive to people who agree with you. But then, that's the test of whether or not you actually believe in democracy.
Something else, between Charlie's USENIX talk and the riots. Isn't one of the biggest disappointments, from a police point of view, the performance of CCTV? No doubt it will help put some of the rioters in jail. But it didn't prevent the riots and neither did it seem to help quell them much. It's possible that the whole idea that potential surveillance (like the original panopticon) is a policing influence isn't as strong as it's made out to be.
Another point; not all crimes are punished or even taken notice of. This is obvious. Less obvious is that the degree to which the police ignore crime is an important political fact. Is it possible that CCTV, by forcing them to make at least a token response to everything that passes in camera range, actually contributed to using up the police strength? In a riot, the police aim is to demonstrate public, mass control. They are usually willing to ignore quite a lot of individual criminality in the process. It's possible that surveillance culture and technology are opposed to strategy.