This work outlines how Macmillan and Listen & Learn Research used social data to learn how to help people who have just been told they have cancer.  Working with Listen & Learn, Macmillan used a social insights approach to finding, appreciating and understanding what it is like to receive a diagnosis. They explored what happens, how people feel, where they go for help, what they needed and ultimately, how Macmillan could help. In this paper, we will discuss how, together, we made this work. From getting a new method approved post-GDPR and gaining internal support, to how this approach to social data was able to unlock previously hidden aspects of life with cancer. Then the results: how Macmillan was able to make changes to service design, communications, and resourcing while feeding into their longer-term strategy.