From 1972 to 1984 Dr Guest was employed in the Water Treatment Industry, eventually becoming Senior Chemist/Trade Effluent Officer for the Essex Sewage Division of Anglian Water Authority. As Trade Effluent Officer he monitored the operation of a very large number of effluent treatment plants, particularly treatment plants for the electroplating and foodstuffs industries.

He returned to University in 1984 to study Corrosion Science and Engineering and gained a PhD in the subject in 1987.

From this time he was employed at CAPCIS Ltd, the Corrosion and Protection Centre of UMIST and the largest corrosion consultancy in the UK. He was involved in a range of corrosion and environmental consultancies for the oil and gas and other industries, and the UK Ministry of Defence.

From 1995 to date Dr Guest has been a Senior Associate at Hawkins. His specialist areas are contamination and corrosion assessments following fires, floods, chemical spillages, natural or man-made disasters. He has worked all over Europe, the near and far East, Africa, Australia and the United States of America.

Dr Guest has been involved in litigation work in both the UK and overseas.

Dr Guest is based in the Manchester office.