Clayton is originally from South Wales but currently lives in Barnsley, South Yorkshire.  He studied metallurgy at Imperial College and gained a PhD from the University of Sheffield looking at offshore corrosion fatigue.  After working for British Steel Technical for three years, as a metallurgical investigator and then corrosion test laboratory manager, he joined Cameron (now called One Subsea), a major supplier of oil and gas completion equipment, in 1990.  He eventually became senior metallurgist and worked on major topside and offshore projects for operators such as BP, Shell,  AGIP, Total, and Conoco. He also had responsibility for the material selection and corrosion prevention for topside and subsea projects and for the metallurgy and welding of equipment including wellheads, BOPs, flowlines, choke valves, risers, manifolds, Christmas trees and associated items.
Since 2000 Clayton has been director of Lloyd-Thomas Consultancy Ltd, providing metallurgical support and training. He has continued to work in oil and gas as well as other engineering sectors, such as power engineering, aerospace and biomedical, has carried out numerous failures investigations and has acted as an expert witness in litigation cases.
He has run over 250 metallurgy courses for companies and colleges on various aspects of metallurgy and is an approved trainer for the AMRC.