Professor Hewitt has been active in computing since the early 1970s and has extensive experience in programming and supporting researchers, scientists and engineers, particularly in supercomputing, data and visualization. In the late eighties he established one of the first parallel processing services in the UK, at the University of Manchester and since then he acquired responsibility for the development of high end computing and high performance visualization services both locally and nationally.

With colleague in CSC and SGI he ran the CSAR HPC service for UK academia from 1998 to 2006, one of very few successful government funded PFI IT projects; its unique feature being the pay-as-you-go capability.

He has been active in the development of e-Science, locally and nationally, including the establishment of the UK National Grid Service and the UK Access Grid Support Centre.

This service role has been complemented by a diverse research and development programme of 48 awards valued at around £20M, with funding obtained from the Engineering and Physical Sciences Research Council (EPSRC), the Natural Environment Research Council (NERC), the Economic and Social Research Council (ESRC), the Department for Business, Enterprise & Regulatory Reform (formerly DTI), the European Union and international companies. He has been a consultant to a number of companies including DEFRA, MOD and NEC. He has supervised 27 MSc and 16 PhD students, and has published over 80 papers, co-authored a book and edited another.

He is an evaluator for EU proposals and has been Chairman of the European Association of Computer Graphics, and Vice-Chairman of the SGI Worldwide Users Group and has lectured extensively throughout the world. He has organized a number of national and international conferences.

His company has provided services to London  Metropolitan University, NEC, DEFRA/MOD, the University of Manchester, Science and Technology Facilities Council, Bangor University, Swansea University and HPC Wales.