Have you approached the Valuation Office Agency?

I used to work in the VOA in London many years ago and I remember the surveys and files were a treasure-trove of information about the buildings. Every commercial and residential building is surveyed, photographed and described - and the archives go back years recording every alteration and change of use. You will be able to find much of the information you seek in those records.

I’ve not worked with the Valuation Office Agency or their data directly, but colleagues have variously requested data or worked with their records. They certainly hold a wealth of information - see for example link [1] below.

It’s relatively difficult to get access, however, and then not possible to share or update independently, as it’s not released as open data.

Part of the Colouring London project motivation is to create open data at the building scale, which can be freely used, updated, validated and built upon.

It’s not necessarily straightforward to release data openly which has been collected under other assumptions, but it would be interesting to discuss which parts of the VOA records might be possible to release as open data, with regard for privacy and sensitivity. Colouring London might be able to help make that case.

[1] https://www.ons.gov.uk/census/censustransformationprogramme/administrativedatacensusproject/datasourceoverviews/valuationofficeagencydata