A ‘go-slow’ protest by London cab drivers has unwittingly sparked a huge surge in registrations with Uber, the business they were protesting against.

The 12,000-strong protest on Wednesday was in opposition to the new app which helps passengers calculate the cost of journeys.

Drivers say this is amounts to a fare meter, which only licensed cab drivers are allowed to use. They say Uber is unregulated, so could be inaccurate and lead to a rise in disputes over trip rates.

New leader of the Rail, Maritime and Transport (RMT) union, Ian Beetlestone, said Uber operated in a "grey area" and that he wanted the protest to shed light on the issue.

Meanwhile, Uber’s UK and Ireland boss Jo Bertram 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.

Pointing growth registrations yesterday, she added: “In fact, today we're seeing an 850 per cent increase in sign-ups compared to last Wednesday. The results are clear: London wants Uber in a big way.”