London's skyline changed radically during the 2000s. In this respect it has much in common with megacities around the world in which the expansion of tall buildings, both for residential and commercial use, has become a defining feature of twenty- first- century urban growth. By 2019, London already had 360 blocks of 20 storeys or more, with a further 510 schemes in the planning pipeline (New London Architecture 2019). Ninety per cent of these are residential (CTBUH 2021), with investors increasingly drawn to the potential profits that housing can make.

However, few planning issues have proved more divisive and London's discretionary and opportunity- based territorial planning system has consistently struggled to provide a coherent strategic overview of how and where such buildings should be placed, and what purposes they should serve. For advocates of a London model their presence is symbolic of the city's openness, pre- eminence and expansion. In more practical terms they provide new commercial and residential spaces that enable the economy and population to grow within a relatively constrained urban environment. Perhaps most significantly they are presented by London model advocates as being representative of future vision for megacities, with claims made that London's planners have much to learn from growing metropolises across the world – notably iconic cities like Dubai and Shanghai – in which tall buildings now dominate urban development.

And yet for critics, their construction is both functionally and aesthetically damaging to London. They decry such forms of development as piecemeal and corrosive of the city's traditional urban landscapes. In the face of new forms of finance and mega- scale proposals, planners, policymakers and citizens have found that established planning regulations are increasingly inadequate and unable to exert control over developers and investors.

In the words of the pressure group the Skyline Campaign (2014: 1) “this fundamental transformation is taking place with a shocking lack of public awareness, consultation or debate. Planning and political systems are proving inadequate to protect the valued qualities of London, or to provide a coherent and positive vision for the future skyline.” Others such as Transparency International (2020) have undertaken powerful in- depth studies of how London's deal- based planning system opens up opportunities for corrupt practices, especially in permissions over tall buildings.