Background
Green social prescribing to connect people with non-clinical community-led, nature-based interventions is gaining prominence as a means of addressing mental health and well-being needs.

Third sector organisations delivering socially prescribed programmes within local communities rely heavily on public funding to support their activity. Financial inputs and transparency need to be clear, efficient, and effective to ensure long-term sustainable creation of social value and public health outcomes.

Methods
This study conducted a Social Return on Investment (SROI) forecast for The Fathom Trust, an emerging Wales-based charity delivering the ‘Making Well’ green social prescribing programme. This community-led, natured-based intervention offers traditional crafting, horticulture, and contemplation to support people with long-term mild to moderate mental health conditions in the Brecon Beacons, Powys.

’Making Well’ programme costs were estimated in consultation with The Fathom Trust and well-being benefits and their estimated monetary value were based on a recent SROI evaluation of a six-month Making Well pilot. Projected 20% overheads including governance, programme development, staff training and fund-raising costs, were incorporated in this forecast to reflect sustainable costs as the charity develops and support a robust estimate of the future social value expected to be generated by the Making Well programme.

Results
This SROI forecast provides a three-year projection of the annual social value created by the ‘Making Well’ programme. The estimated forecast cost of programme inputs was £797 per participant and the net value of well-being benefits were £4,313 to £6,130 per participant, giving a range of social value ratios between £5.40 to £7.70 for every £1 invested.

Conclusions
SROI forecasting for socially prescribed interventions delivered by local third sector organisations can help organisations demonstrate transparent and effective investment of public funds. This, in turn, can help support optimal social value creation and long-term public health outcomes into the future.