He has a number of national roles and advises a several national organisations. Professor Rees is a Past President of the British Elbow and Shoulder Society (BESS). He has held a past fellowship with NICE, promoting healthcare guidelines and standardisation of patient care. He has authored many national guidelines and works closely with the National Joint Register (NJR), NIHR, British Orthopaedic Association, the MHRA, and the NHSI Getting it Right First Time Programme (GIRFT).