I spent my academic career in the School of History of Art and Screen Media at Birkbeck, University of London, where, since retirement, I have beenVisiting Professor. My research and publications have focussed on English medieval architecture with a particular interest in the inter-relationship between architecture and its social, political and liturgical functions, as exemplified in my book The Formation of English Gothic (Yale 2006). More recently my interests have turned to Islamic architecture. I served as Honorary Secretary of the BAA from 1968-72, as joint editor of the Medieval Conference Transactions from 1978-82, and as President from 2007-2010. I have also served as President of the Society of Architectural Historians of Great Britain 2000-2004, having been Honorary Editor of Architectural History from 1985 to 1992. I was a member of the Cathedrals Fabric Commission for England from 2001 until 2011 and have been a member of the Fabric Advisory Committee at Southwark Cathedral since 1992, serving as chairman 1995-2009. I am currently a Commissioner of English Heritage.