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Shields highlighted that one way Britain was working to overcome these challenges was by introducing things like the "Exceptional Talent" visa for international leaders in science, engineering and tech.
"We (Tech City UK) are trying to look at this case by case and to help companies… get those visas," she said.
Taken alone, London's tech sector employs only slightly fewer workers than those in New York and San Francisco/Silicon Valley, according to South Mountain Economics.
London has around 382,000 workers in the sector, just below San Francisco/Silicon Valley's 397,000 and New York's 411,000. Nonetheless, report author Mandel said the figures places "the city within the top echelon of global tech regions today."
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Separate research by Oxford Economics, also published Monday, found that London's digital tech sector is expected to grow at a rate of 5.1 percent per year.
This will boost Britain's gross domestic product by £12 billion ($20.37 billion) over the next decade, according to the report, creating 46,000 new jobs in the capital.
Speaking at the launch of London Technology Week, Mayor of London, Boris Johnson, said these forecasts were realistic. However, he stressed it was time to question why London – as Europe's biggest digital hub - hadn't yet produced a tech giant like Twitter, Google or Facebook.
"Is it because of a British diffidence about making billions of pounds? Is it because we don't have the right kind of kick-ass business people here in London? Is it that the banks and venture capitalist industry aren't as imaginative and proactive as they could be?" he asked.
Johnson denied that "all the big ideas" had already been taken by companies like Twitter, Facebook and Google. "I don't believe that to be the case. This is just the beginning of an industrial revolution in which London has a huge chance of being the center," he added.
—By CNBC's Katrina Bishop