London is a snarl-up at the best of times, of course, so Lord knows what it will be like when black cab drivers begin their protest at 14:00 in Trafalgar Square – with no less than 12,000 expected to take part in the hour long demonstration.

So what's this all about? The Uber service offers background checked private drivers for hire across London (as well as Manchester, Dublin, and over a hundred cities globally), but the drivers of black cabs are unhappy because Uber drivers aren't subject to the same regulation as licensed cabbies. Because Uber uses an app to work out the cost of a fare, the cabbies argue that this is in effect equivalent to having a taxi meter – and only black cabs are legally entitled to use a meter in London.

Steve McNamara, head of the London Taxi Drivers' Association, has previously said his issue isn't with the private hire firm, but with TfL (Transport for London) and its lack of regulation: "Our beef is not with Uber but with the regulator which is not enforcing the law and kowtowing in the face of Uber's money."

McNamara further explained that Uber was backed by Google and Goldman Sachs.

TfL remains unimpressed, naturally enough, and according to the Beeb, Garrett Emmerson, the organisation's COO for surface transport, said: "A number of taxi drivers are set to cause pointless disruption for Londoners over a legal issue that is down to the courts to decide upon. TfL will work with the Metropolitan Police to do all we can to keep central London moving. However, given the scale of the likely disruption, we would advise drivers to avoid the area if at all possible."

Protests are also taking place in other major European cities, including Berlin, Paris and Rome (not for the first time, either – this has been a long running dispute).

A photo posted by on

UPDATE: Our own Andy Evans has caught a glimpse of the havoc first-hand. Check out his clip above.