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The Mayor of London The London Assembly

33 boroughs, two babies and one city modelling platform

We’ve been hard at work since our last update – in that time we’ve delivered our first release of Witan, and two babies! Our city modelling platform is now live and our first users in London have been given access this week.

On-demand demographic projections to meet housing demand

Witan is now able to generate demographic projections linked to demand for housing for London, using GLA’s own models. This means that officers in the 33 London borough councils can enter housing data projections and see how this affects the spread of the population across wards in the borough for years going all the way up to 2041.

These numbers are useful to the boroughs for planning in many ways – for example, to carry out school roll projections. Previously, this process used to take weeks of specialist GLA staff time, and would typically happen once a year. Now we’ve automated the process, allowing boroughs to run their own projections at any time using GLA’s models, as often as they need to, creating new projections in under five minutes.

Excellent & functional, but not sexy

We’ve opened up Witan to the boroughs in London for testing, and as feedback comes in from the boroughs we will be using this to improve the user experience. Once borough officers experience the freedom of generating their own projections, we hope that the true potential of the platform will start to be realised – such as the benefits of moving beyond the limitations of Excel.

Our favourite description so far is from Andrew Collinge, Assistant Director of the GLA Intelligence Unit, that Witan is ‘excellent & functional, but not sexy’. We’re happy that we are building something with substance over style!

However in the next phase, we’ll start putting bells and whistles onto the platform, including visualisations, group sharing, a data API and a metadata API. We’ll also be building in our next set of models which feature economics projections around jobs and commuters.

Would this work in your city?

We’re looking for pilot cities and local authorities to test Witan outside of London. If you are interested then please sign up to the Witan public mailing list on the landing page at or contact us on

Mastodon C is a small cloud computing company working closely with the GLA and funded by Innovate UK’s SBRI programme to develop a city-modelling platform. One of our aims is to open up government processes where possible and appropriate, so we are working in the open as much as possible.

To explore Witan and answer any queries you may have, please visit the Witan guide, checkout the project, UI and app code (and star the github repos if you really like them), or email us at

We’d also really appreciate you sharing this blog with others you think might be interested in what we are doing.

Elisabeth Weise is Delivery Manager at Mastodon C