Black Cab Demo Causes Central London 'Gridlock'
Parts of central London were gridlocked after thousands of black cab drivers took industrial action at Trafalgar Square.
Up to 12,000 black cabs headed to the centre of the capital with the aim of causing traffic chaos.
Helicopter footage showed long queues of cabs across Westminster Bridge and along Whitehall to Trafalgar Square.
The traditional cabbies were protesting at Transport for London's regulation of rival cab service Uber.
The Google-backed app allows users to order a car at the touch of a button, and the fare is calculated using GPS tracking.
But traditional cabbies say this is effectively a taxi meter, which only black cabs are legally entitled to use in the capital.
Sky's Ashish Joshi said that Trafalgar Square was "gridlocked" just before the protest officially started at 2pm.
He said: "This is technology against tradition. It's the new Battle of Trafalgar."
One cabbie with 15 years of experience told Sky News: "It's got to be a level playing field. England are playing Italy on Saturday, what if Italy turn up with 15 men against England?"
He added: "We love competition, we thrive on competition in this city, but it's got to be a fair competition."
Uber general manager Jo Bertram defended the company's business model, saying the number of app downloads has soared.
She said: "Londoners are voting with their fingers, tapping the app in support of new and innovative services as we see our biggest day of sign-ups in London today since launch two years ago.
"In fact, today we're seeing an 850% increase in sign-ups compared to last Wednesday."
Earlier the app goaded black cab drivers by urging them to sign up to their pre-booking app, saying it gave greater "choice for consumers".
However, the cabbies dismissed it as a PR stunt.
There were similar demonstrations in Paris, Madrid and Barcelona.