Work is underway on 25 new schemes across the capital as cranes spring up across the skyline.

Anthony Duggan, head of research at Drivers Jonas Deloitte, said: “This survey records a dramatic positive change in construction activity as anticipated in our last report. The race is on to deliver schemes to take advantage of the dwindling supply of Grade A space in 2012 and 2013.”

Just under half of the schemes under construction are 100,000 sq ft or bigger.

Duggan added: “Large buildings in the West End, such as British Land’s Regents Place and Legal & General & Mitsubishi’s Central St. Giles have been star performers over the last year – developers have recognised this trend and are looking to cash in on this type of occupier demand.”

Matthew Elliott, head of transactions at Drivers Jonas Deloitte, said: “The big story, perhaps the only story, is the building of the new City towers. If all are built we could see over 200 tower floors coming to the market at a similar time in 2014/15 – an unprecedented situation – and this excludes The Shard being built on the other side of the Thames.

“Some will worry that this will lead to oversupply and falling rents, but others say that this is a further sign of confidence, a sign that London remains the global financial centre. Everyone is talking about it but the market doesn’t yet know how this will play out.”