London's relatively clear skyline, once dominated by St Paul's Cathedral and, later, by Canary Wharf, the Gherkin and the Shard, is likely to get an awful lot more crowded over the coming years, with almost 250 tall towers proposed, approved or already under construction.
A survey by the New London Architecture (NLA) think tank suggests that 236 buildings of more than 20 storeys could be on the way, 189 of which are intended to be residential blocks. Eighteen are planned as office developments, eight as hotels and 13 are due for mixed use, while one is to be an educational institute.
According to the study, based on local authority figures, 48 per cent of the towers have been approved and another 19 per cent are under construction. Thirty-three of the 236 will be between 40 and 49 storeys high; 22 will have 50 or more storeys.
At the heart of the new tower boom is Tower Hamlets, in east London, which is to be home to 23 per cent of the new buildings. Projects in east and central London account for 77 per cent of the total, although south London also faces vertical development. Between them, the boroughs of Tower Hamlets, Lambeth, Greenwich, Newham and Southwark will have 140 of the towers.
Peter Murray, director of the NLA, said the survey had been prompted by remarks made by the London mayor, Boris Johnson as he announced his revised housing strategy last year.
"He said that we've got to build 42,000 new houses every year, but it won't mean towers are 'popping up all over London', as he put it," said Murray.
"But then we started looking at some of the statistics coming in from various boroughs as to the sorts of buildings they were giving permission to, and we realised that actually it does mean that: just like in the 1960s, when we had to build a whole lot of houses, we are going to go higher than I think a lot of people had imagined."
And, judging by his comments, higher than Johnson imagined as well.
The survey is the think tank's way of attempting to gauge the effect the new towers will have on the London skyline.
"I've got nothing against towers at all, but we need to understand what the impact is," said Murray. "We need to have a planning system that is fit for purpose: to provide a vision for the city in the future and to control the way that development takes place in a reasonable manner."
Murray, who believes the current system could do with some "beefing up", points to the huge pressures on the Greater London Assembly and local authorities to deliver more housing at a time of very high land prices. Faced with such prices, developers are understandably keen to build high, he says. The situation is further compounded by increasing demand for housing in London from east Asia, where tall buildings have long been part of the urban landscape.
Edward Lister, London's deputy mayor for planning, said a strategic approach was required to balance the protection of the skyline with the need to house one million more people and create more than 500,000 new jobs over the next few years.
"What we can't do is try to impose some kind of freeze on the skyline and suspend the capital in stasis," he said.
"The key issue in any discussion of London's skyline is whether a building makes a positive contribution to London's urban realm, protecting the things we value about our city while helping us meet the challenges of growth and ensuring the continued prosperity of London and Londoners."