Gillian Catherine Leng, Lady Cosford CBE is a British health administrator, academic, visiting professor at King's College London and the former Chief Executive of the National Institute for Health and Care Excellence (NICE), where she was responsible for several programmes and guidelines including the guidelines on COVID-19.

She has been involved in the Cochrane collaboration since its foundation, and has worked on clinical trials and epidemiological research in public health medicine.

[3] She worked on clinical trials and epidemiological research in Edinburgh, and in London as a consultant in public health medicine.

[7] Leng delivered a presentation for the European Society of Cardiology at an event titled Digital Health 2019.

[9] She is visiting professor at King's College London, and teaches at NUS Saw Swee Hock School of Public Health.

[14] The commission is a partnership spawned out of COVID-END, with leadership from McMaster University and the Ottawa Hospital Research Institute.