The latest crane survey by Drivers Jonas Deloitte, which measures the number of cranes on the capital's skyline, believes lower build costs are partly behind the recent growth.
According to their research, 9.2m sq ft of office space is under construction in London, 28% more than six months ago.
Projects under construction include the Walkie Talkie skyscraper by Land Securities and Canary Wharf Group, and the Cheesegrater by British Land and Canadian group Oxford Properties.
Anthony Duggan, head of research, at DJD, said: "While construction continues to rise in the core City and West End markets, our research also shows that activity has returned to King's Cross and the Docklands, as well as a further increase in activity along the Southbank. This is a sign that developers feel that the low levels of construction – compared to historic trends – and lower building costs are compelling."
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