Timothy was elected Principal and Vice-Chancellor of the University of Edinburgh in October 2002. He has a BSc in Mathematics and Experimental Psychology from Sussex University and a PhD in Computer Science from the University of Leeds. He carried out artificial intelligence research at the University of Texas, the Xerox Palo Alto Research Centre and the University of Edinburgh.

In 1997 he became Master of Birkbeck College and was awarded a Chair in Information and Communication Technologies by the University of London. In 2000 he was appointed Provost of Gresham College and in 2001 Pro-Vice-Chancellor of the University of London. He became a trustee of the British Council in September 2003. He held these two posts concurrently with that of Master of Birkbeck. In 1978 he joined the Open University where he was awarded a Personal Chair in Information Technology and Education and in 1994 was appointed Pro-Vice-Chancellor for Quality Assurance and Research. In 1999 he was elected Fellow of the European Co-ordination Committee for Artificial Intelligence, in 2001 admitted into the Freedom of the City of London, and in 2004 elected Fellow of the Royal Society of Edinburgh.

He was made in Knight Bachlelor in the 2008 New Year Honours.