The Hoxton Chronicle. 065 - Urban Grain

"Sir, if you wish to have a just notion of the magnitude of this city, you must not be satisfied with seeing its great streets and squares, but must survey the innumerable little lanes and courts. It is not in the showy evolutions of buildings, but in the multiplicity of human habitations which are crowded together, that the wonderful immensity of London consists."
Boswell - Life of Johnson

Johnson’s epigram is more than a love letter to London it reveals something fundamental about what makes cities endlessly fascinating and enriching places to live. It also tells us something about urban geography and what, in urbanists’ jargon, is called ‘the urban grain.’

The basic geography of all cities comprises streets that divide the land into city blocks, which are then further subdivided into individual building plots. The number of blocks per hectare (block ratio) and plots per hectare (plot ratio) provide a dry measure of the urban grain that urbanists love to discuss and Samuel Johnson loved.

In the 100 ha of London that is the setting for all the Hoxton Chronicles, there are 120 urban blocks, giving a block ratio of 1.2 blocks per hectare and 1159 building plots, giving a plot ratio of 11.59 plots per hectare. These two ratios combined provide an arithmetic measure of Hoxton’s urban grain.

A striking conclusion from the study of historical maps, repeated in cities worldwide, is the loss of urban grain as cities modernise. New and redeveloped parts of historic cities such as London have much larger city blocks (low block ratios) and very much larger city plots (low plot ratios).

As ever, the drivers of this trend are economic. For city developers, it is much more efficient to construct a building on a big building plot with large floors at each level with the minimum area used to configure circulation and service cores rising through the building efficiently. A development of this type results in the maximum possible rentable area for occupiers and, hence, development profit. With the redevelopment of historic city areas, it is economically desirable to combine many small plots to form a single large plot for a large building. This process of ‘site assembly’ can result in building plots that take up an entire city block that is then developed as a single large building.

Development economics is not the only force reducing the ‘granularity’ of the city. Post-war city planning had an even greater impact. Here, the motivation to create large development plots was not profit but social engineering. The planners’ modernist vision for the city was of multistorey blocks of flats set in large areas of landscape parks. Open space was seen as the panacea for any number of urban evils, including ill health, poverty, deprivation, congestion and crowding. Hundreds of streets and many thousands of small, terraced houses were demolished to achieve this futurist vision. Although the new buildings were tall and architecturally dramatic, they accommodated the same number or fewer households than the terraced buildings they replaced. It was a strategy to replace city living with an alternative high-density version of a garden village or a suburban version of urbanity.

In Hoxton both the forces driving down urban granularity are apparent. To the north are large areas of post-war planned estates based on the park and tower model. To the south, the land assembly process generates the conditions for large, city-block-scale skyscrapers. Mitigating between these are the conservation areas of the Shoreditch Triangle, an urban area created mainly through Victorian commercial development in the era before formal town planning. Here, the tradition of urban blocks divided into smaller building plots endures accommodating a mix of constantly changing uses. It is by far the most popular area of Hoxton.

Sir Patric Abercrombie, architect of the post-war London plan, considered small-scale entrepreneurial urban development as “The opportunity lost”. He wrote:

‘The opportunity? The Blitz has cleared some sites and we must clear many more – but for what? Has the Blitz cleared our vision too and made it possible to see what London might be? And if we can see this, have we the imagination and power to realise our hopes, or shall we return to the old unplanned city blocks, to the same old wild activity of private speculation, to recreate the same old jumble of courtyards and streets and competing facades? An inheritance for the future as grim as anything we know today. The land speculators’ boards are up….. OR can we plan our London; give it order and efficiency and beauty and spaciousness? Can the County of London Plan become the real plan for London?’

The County of London Plan – EJ Carter and Erno Goldfinger

Today it is the old unplanned city blocks and – the same wild activity of private speculation - the same old jumble of courtyards and streets and competing facades that is afforded the protection conservation areas by the planning authorities.

In the modern city, the economics of both large-scale corporate developers and large-scale municipal corporations drive out medium and small-scale owners of city land and buildings. Citizens, as active agents in the city-making process, are reduced to passive community consultees or tenant consumers of a city made by big capital and big corporations. The city that Johnson loved, and Abercrombie despised is poorer for it.