Thanks to Aron Cronin for this article from The Guardian of 12 January 2019.
The Garden Classroom, which is organising this event, won the Lisa Pontecorvo Award in 2015 (for its outstanding work and contribution to people and spaces).
Anna McKane arranged for a group of enthusiastic runners from goodgym to spread mulch around the roses in Thornhill Square Gardens. They appeared to have enjoyed both the running and the thought of helping the community, and we should be able to enjoy the outcome. There are more pictures, and more details of what they did, here.