Tim Porter see also his nLab page
Ieke Moerdijk (also in Sheffield for part of the time)
Here are some other lists of Home Pages
Topology related
Algebraic Topologists (this appears not to be maintained any more)
Other
This page is maintained by Andy Baker (a.baker@maths.gla.ac.uk), please email me if you want to be added to the list or spot any errors
(updated 04/03/2017)