Diarmaid has nearly two decades of experience in global health, HIV, and access to medicines policy, advocacy and campaigns. He was Advocacy Manager of STOPAIDS, a UK-based coalition focused on the global AIDS response, for six years and has worked on HIV programmes in Tanzania and Ethiopia. In 2017 he founded Just Treatment, a patient-led campaign demanding fair access to medicines on the NHS and reform of the pharmaceutical industry. He has represented NGOs on the board of Unitaid, a multilateral agency focused on improving access to innovative health commodities in the developing world. He is a Shuttleworth Fellow.