Incremental housing extensions and formal-informal hybridity in London, United Kingdom. Questioning the formal housing imaginaries in the ‘North’

The incremental housing development is rarely discussed in the context of the North. While perceived as a niche modality, its analysis provides a valid opportunity to question the perceptions of local housing markets as fully formal and document the spatial and morphological outcomes of more inconspicuous, long term and decentralised housing processes. This paper fills this gap by analysing obscure yet prevalent processes of backyard extensions in London, United Kingdom. The morphological analysis presented documents this phenomenon's scale and main characteristics through tracing changes in built form using remote sensing imagery between 2003 and 2021. It focuses on changes in the backyards of four residential blocks in four case study areas with varying income levels across the London metropolis. By discussing these transformations in the context of legal ambiguities, densification, and deregulation, we point to the informal/formal hybridity of the local housing market. This nascent study documents that incremental development happens at a rapid pace and scale and occurs across all income levels. In theoretical terms, the paper questions the dichotomic categorisation of informality and formality in a context of a Northern city and points out the benefits of engaging with experiences of incremental development across geographic boundaries.