Born Edinburgh, first degree Witwatersrand, postgraduate diploma at The Courtauld; lectured at the universities of the Witwatersrand and East Anglia, and then held the posts of Professor of Fine Art at Edinburgh and Director of The Courtauld. Fellow of the British Academy, the Royal Society of Edinburgh, the Society of Antiquaries of London (of which he has been President), and the Society of Antiquaries of Scotland.
- Medieval and especially Romanesque architecture
- Medieval architectural planning and metrology
- Art historical theory