From 2003–2007 he was Gresham Professor of Astronomy at Gresham College, London, and he has been appointed as Gresham Professor of Geometry from 2008–2011; only one person has previously held two different Gresham chairs.
Årem 2003-2007 var han Gresham-professor i astronomi vid Gresham College i London, och han har varit utsedd till Gresham-professor i geometri åren 2008-2011; endast en person har tidigare haft två olika Greshamstolar.