A solid blockade of iconic black cabs stretching from Big Ben to Trafalgar Square and Buckingham Palace froze the traffic in Central London today as European taxi drivers said “No” to the rise of the ride-sharing app Uber.

Undeterred by coordinated protests in Paris, Madrid, Berlin and beyond, the San Francisco start-up taunted its opponents with claims that the demonstrations had boosted membership numbers and suggested the traditional drivers hailed from the “Dark Ages.”

In London, where licensed “hackney carriages” have been operating for 300 years, cab drivers said they were proud of their history and that the arrival of Uber was putting the public at risk. Officially licensed drivers, who buy their own vehicles for more than $60,000, undergo criminal record checks and between three and seven years of training.

Drivers are furious that Transport for London is relaxing its own rules, which ensure that taxi meters can only be used in official black cabs. The demonstration strangled the flow of traffic in London from 2 p.m. onward, with some commuters complaining of hour-long traffic jams.

"This protest is about the ripping up of established regulations in the name of greed and private profit and the decimation of London’s black cabs," said Mick Cash, the acting general secretary of the Rail, Maritime and Transport union.

Since Uber was founded in 2009, there have been a series of allegations about the behavior of their drivers, one of whom was arrested on suspicion of kidnapping a woman in Los Angeles last month. Serious concerns have also been raised over the amount of personal information that is shared with the driver.

Those concerns have done little to curb the explosive global growth of the Uber app, which allows people to order a car to meet them without the hassle of trying to hail a taxi. Cab drivers in Europe today claimed that passenger safety should be safeguarded even though more and more people were succumbing to the temptation of their convenient but unlicensed rivals.

“It’s very dangerous letting Uber in,” Grant Davis, who has been driving cabs for 26 years, told The Daily Beast. “Say you have a problem with me—I pick you up, and me and you have a few words: I say, ‘Oh, fuck off, you wanker! Get out.’ You’d take my number down, and my head’s on the chopping block. I have to go up and explain myself and if it ain’t right they'll suspend me or take my license away.”

Davis, 50, spent four years studying London’s roads, alleys and bridges before qualifying to become a licensed driver. Now chairman of the London Cab Drivers Club, he has a meeting with Boris Johnson, the Mayor of London, tomorrow. “As soon as we sit down I know Boris’ bum is going to be twitching,” he said. “I’m going to tell him: If you want to mess with our livelihoods, what you’ve had today we’ll have every week, because at the end of the day what have we got to lose, except our future?

“You’ve got mini cab drivers in London using Sat Navs in San Francisco and paying tax in Holland, and they think it’s hunky dory. Well, I beg to differ, actually,” he said.

So did drivers across Europe, who launched their own idiosyncratic protests Wednesday. In Paris, drivers implemented “escargot” measures and drove at a snail’s pace; in Madrid, taxi drivers left their cars behind and marched through the city on foot; while Milan’s thousands of drivers took the day off entirely.

Protests against Uber were held in various U.S. cities after the app launched but the drivers in Europe tend to be more politically active and heavily unionized.

Traffic may have been snarled across the continent, but Uber showed no signs of backing down. A spokeswoman claimed that the increased attention had resulted in an 850 percent increase in sign-ups.

“Unsurprisingly, the Licensed Taxi Drivers’ Association (LTDA), which is stuck in the dark ages, is intent on holding London to ransom,” said Jo Bertram, Uber’s UK and Ireland general manager, in a statement. “London wants Uber in a big way.”