You drew helpful attention to the many institutes for advanced study that have sprung up, or are in the process of emerging, on UK campuses ("The perfect brainstorm", 20 March). But in important respects it is misleading to compare these, as you did, with the Institute for Advanced Study at Princeton (not, as you wrote, Princeton University, from which it is independent) or the Center for Advanced Study in Behavioral Sciences at Stanford.

Most UK institutes, albeit interdisciplinary, are local, and often tied to local pedagogic programmes and priorities. Typically, a handful of fellows come for days or a few weeks to lead a seminar or colloquium that few outside the university where they are located learn anything of.

While this is valuable, it deserves no comparison to the US institutes - or to the Wissenschaftskolleg in Berlin, the Netherlands Institute for Advanced Study or the Humanities Research Centre at Canberra - which are more truly modelled on Princeton.

At these institutes, 40 or 50 fellows are in residence for a year, usually with no duties or tied programme, and what emerges is a genuine interdisciplinary and international community, daily conversation and (I speak from personal experience of four such centres) rich and productive research collaboration.

ÁñÁ«ÊÓƵ

It is, as your columnist Felipe Fernandez-Armesto observed in describing the opening of such a new centre at Madrid, these rich benefits that England loses out on in being one of the only advanced academic cultures with no national Institute for Advanced Study.

For intellectual and political reasons, for the advancement of knowledge, creative thinking and critical engagement, we urgently need one. Welcome though they are, the small-scale, local campus initiatives, with little international visibility, are in no way a substitute for a national centre.

ÁñÁ«ÊÓƵ

Kevin Sharpe, Professor of Renaissance studies, Queen Mary, University of London.