Sir John was a GP for 29 years. His practice won several national awards and in 2000 led to him being asked to create and head the National Primary Care Collaborative, a large scale change programme covering 32 million patients in 40 months. He subsequently designed other large scale change programmes in Scotland, Australia and other countries. He also worked in Education, successfully raising performance of underperforming pupils in 400 schools.

He has been a keynote speaker at many international conferences on large system change, quality and safety and has spoken at Davos and Bilderberg meetings. He was a member of the National Quality Board, National Clinical Lead for Quality and Productivity at the Dept of Health in England and subsequently Chair of an Independent Commission on Whole Person Care. He was Senior Independent director at the Care Quality Commission in England until the pandemic, and in 2023 an advisor on NHS reform to the then Shadow Secretary of State for Health and Social Care until the general election and subsequently Strategic Advisor to the Secretary of State to Oct 25.

He received an OBE in 2001 for services to patients and a Knighthood in 2003 for services to the NHS.