The right to protest is also enshrined in UK law (within a huge number of constraints).

Other (one-off or infrequent) protests such as Critical Mass certainly obstruct free passage along the highway, but they are tolerated.

Critical Mass isn't a protest, it's a procession, and it's not tolerated, it's operating perfectly within the rights of its participants: http://www.publications.parliament.uk/pa/ld200708/ldjudgmt/j...

Fair enough, but there's enough stupid/aggresive behaviour on the London CM for me (and a whole bunch of other cyclists I know) to stop attending it.

There are ways to hold a protest/demonstration/march legally [1], though I've no idea a.) whether what they plan would fit what's allowed on that front b.) whether they have informed police etc.

Could well be they're going down the "prove we're not just normal congestion" road.

Edit: forgot the link. [1] https://www.gov.uk/protests-and-marches-letting-the-police-k...

There has been many go-slow protests before in the past. In effect, the police will not charge anyone with this.

This was my thought. Purposely blocking traffic is illegal and I hope everyone of these taxi drivers get fines. This is like a child throwing a fit when they don't get their way...

How easy would that be to prove? At what point does a group of vehicles that happen to be driving down the same piece of road turn into a 'wilful obstruction'?

When they announce it on the BBC beforehand?