The way we report and measure impact is always changing, adapting to the places and people who benefit from development and intervention. On a smaller scale we know we can surface the right stories and data to win over hearts and minds but on a national level, HM Treasury also has a part to play.  

In June, HM Treasury issued a review of the Green Book, the key guidance “on how to appraise policies, programmes and projects”i. When we go right back to the root of our social impact calculations, this is the key source. Before we add the regional weightings, the drop off or the discounting (looking at what might have happened anyway or had a knock on elsewhere), the Treasury is setting the tone and ensuring data is robust and transparent.  

The review had six key findings. We have focused on three of these here which relate directly to our day-to-day work. We are excited to see how this helps to ensure we remain accurate in our impact articulation, delivering the best possible outcomes for local people through development.  

1. Improve emphasis on place-based objectives 

HM Treasury has proposed working alongside regional government to ensure data is further embedded within the local context. This will mark a positive step towards ensuring that we can compare projects across sectors and regions. We often talk about how a home delivered in Newcastle has a very different impact to one in Cornwall, based on urban density, socio-economic context, housing need and access to facilities, green spaces and infrastructure. By looking deeper into local links and working with the Ministry of Housing, Communities and Local Government, as well as the Department for Transport, these figures will continue to grow in accuracy, preventing overclaiming and reducing public distrust in the quantification process.  

2. Improve the Green Book guidance on appraising transformational change 

“HM Treasury will commission an independent review of the Green Book discount rate to make sure that the government is taking a fair view of the long-term benefits that arise from transformational investments.”1  

When we talk about large scale urban renewal, new towns and redevelopment, we know that many of the broader social impacts can’t be truly quantified and reported. Instead, we rely on the stories of lives changed and communities brought together to show that development has a ripple effect beyond the spreadsheet’s control. However, we hope this review will help us establish which benefits can be attributed to developments on a site specific basis and critically, how long that benefit is felt for. 

3. Reduce overly long and complicated guidance 

By 2026 we expect to see a much shorter Green Book. We know that communication, language and accessibility are key in any document, from government papers to development websites. If, as an industry, we cannot understand it, how do we expect the public to play an active role in the conversations around construction, social impact and legacy building?  

Critically HM Treasury “will make clear the level of detail that is proportionate for business cases of different levels of cost and complexity”ii. So often, when working on sites of a smaller scale, clients feel that social impact reporting is too big, too baffling and unnecessary. The simplification will help to dispel this myth and offer proportional reporting and figures in a more digestible and straightforward way.  

To keep updated with these changes as they pass through policy along with other helpful news, sign up to our e-shot, here. 

If you would like to learn more about social impact reporting, both the quantitative and the qualitative side, our social impact team is on hand and would love to talk more. Get in touch here. 

1 https://www.gov.uk/government/publications/green-book-review-2025-findings-and-actions/green-book-review-2025-findings-and-actions#:~:text=HM%20Treasury%20will%20update%20the,constitute%20poor%20value%20for%20money

i https://www.gov.uk/government/publications/the–green–book–appraisal–and–evaluation–in–central–government/the–green–book–2020
ii https://www.gov.uk/government/publications/green–book–review–2025–findings–and–actions/green–book–review–2025–findings–and–actions#:~:text=HM%20Treasury%20will%20update%20the,constitute%20poor%20value%20for%20money