Gavin trained as a microbiologist at Bristol University, followed by PhD training at the University of Birmingham under the supervision of Prof. Jeff Cole. During his PhD work he characterised the periplasmic nitrate reductase, NapA, from E. coli and also and also contributed to the initial work on the Tat (or Mtt) system (with Prof. Joel Weiner, Alberta Canada). He moved to a postdoctoral position at the John Innes Centre to continue work on E. coli and here started a project in the lab of Prof. Mike Merrick on the E. coli ammonium transporter AmtB. His interest in solute transporters continued with his move to Sheffield to work on tripartite ATP-independent periplasmic (TRAP) transporters in the lab of Prof. David J Kelly.
After his move to a faculty position in York in 2002, Dr. Thomas has continued his work on TRAP transporters and his group have developed the SiaPQM sialic acid transporter from Haemophilus influenzae as a model system for studying this novel family of secondary transporters. His research on E. coli K-12 has also focused on the effective utilisation of the genome sequence, which led to the creation of the EchoBASE database and involvement in the recent reannotation of the genome. This work has also lead to work on bacterial symbionts of insects, which are bacteria with reduced genomes that are, remarkably, subsets of the E. coli K-12 genome.