TrafficMaster sells clients' location info to UK.gov
Pay for your own spy in the cab
Let's say the dark Orwellian future has arrived, and as a British motorist you pay a nasty £500+ levy on a new car so that it can come with built-in cell-netted sat nav spy all complete. Then let's say you now want to make a journey that you'd prefer the authorities were unaware of. And then let's say you don't want to buy a cheap secondhand car with a few months left on its MoT - for probably £100 or less - and give false details on the change-of-ownership forms. For some reason, you want to go in your own car.
OK. Kit yourself out with a combo cellphone and GPS jammer - a quick trip to the States, or call to a friend there who'll forward stuff by post, and you can buy these legally. (You'll be able to buy them, one might submit, in UK street markets for cash within days of any GPS-based road pricing scheme going live.)
If you don't want to spend money or possess any illegal kit, find the antennae of the spy system and block them with good old tinfoil - always the friend of those wishing to escape government spies. Test your work with a short, innocuous journey; if you don't get billed for it by the road pricing authority, you can take it that you know how to cut off your car's spy system. (Or that the government is specifically watching you and being cunning about it, but if that's happened you're being followed by a surveillance team - a risk we all face already.)
Now make your secret trip, then turn off the jammers or take away the tinfoil, and go legit again. Don't worry about your system's downtime being noticed - car batteries go flat or get disconnected, vehicles get parked in metal sheds or underground. The authorities can't chase up every instance of a car dropping off their plot.
And you've done it - fooled the system. GPS (or, maybe one day, Galileo) based tracking is easy to beat on its own. Now you just need to worry about the ANPR numberplate-reading software in the road cameras, already rolled out in the London congestion zone - but again, that's not a big deal for occasional journeys.
Find another car the same make as yours and copy its plates (a thermal printer which can churn out handy waterproof stickers to go over your easy-made blank plate is far from expensive. If you can sort out a delivery address and credit card which don't point to you, just order online).
The guy whose plates you used will get an erroneous road-pricing bill, but even if the authorities can tie his subsequent complaint to your illicit trip, they'll struggle to prove that you used illegal plates - or even that you went anywhere - unless you give them other evidence.
Nationwide realtime ANPR joined up with in-car GPS? Now the government snoopers are in with a fighting chance. It'll be really difficult and troublesome to avoid paying the road pricing, but you can still avoid being tracked.
Buy that cheap secondhand motor for cash and enter false registration details. Use the same ones when you insure it, and don't forget to pay for the insurance by cash or postal order*. If you don't pay the road pricing on the ghost car, after a while you'll have to abandon it and start again, or you'll get pulled over by the plods. Also, don't drive to and from your ghost car in your legit car: walk or ride a bike or something. (Leave your normal-life mobile behind, too.)