●Completed his PhD at 1979, where he studied the enzymology and molecular genetics of purine biosynthesis in Escherichia coli.
●For the following ~five years HJG worked at the PHLS Centre of Applied Microbiology and Research, where he learnt molecular biology techniques, which he used to isolate and study genes relevant to the NHS.
●1985 joined Newcastle University as a New Blood lecturer. HJG joined the Department of Agricultural Biochemistry and Nutrition. His role was to introduce molecular biology into livestock biochemistry and nutrition research.
●1991 HJG was promoted to senior lecturer and the following year (1992) he was awarded an established chair in Agricultural Biochemistry and Nutrition.
●2008 he was appointed as an Eminent Scholar in Bioenergy working in the Complex Carbohydrate Research Center (CCRC) at the University of Georgia, Athens, USA. During his two years in the USA he learnt start of the art methodology in carbohydrate chemistry
●Returned to Newcastle University in 2010