It was with immense sadness that we received news of the death of John Turner on July 24th, 2011 at his home in Queanbeyan, outside Canberra.

John was a towering figure in social psychology as a result of his work on social identity theory in the 1970s and self-categorization theory in the 1980s and 90s. These theories changed the landscape of social psychology and had a huge impact on many other disciplines — from economics and geography to politics and theology. Amongst many other things, John's ideas provided the theoretical footing for the design of the BBC Prison Study, and his commentary on this was characteristically rich, insightful and compelling.

John was a wonderful mentor to both of us. He supervised our PhDs (Steve's at the University of Bristol, Alex's at Macquarie University), and put us on a steady and sure course that has provided us with direction and purpose throughout our careers. As well as being a brilliant intellect, he was also a magnificent friend, whose company it was always a great pleasure and privilege to share. We miss him terribly at both a personal and a professional level, and our lives are as much diminished by his death as they were enriched by his life.

A full obituary was published in The Guardian on September 7.