John has a background in sports and exercise science. He completed his bachelor’s degree from Swansea University, UK, in 2004, and his master’s degree from University of Wales Institute in Cardiff, UK, in 2005.

In 2014, John graduated with a Bachelor of Medicine and Surgery from the Cardiff University School of Medicine, UK. He became a member of the Royal College of Surgeons in 2016 and is currently a Trauma and Orthopaedic Specialist Registrar working in the south of England.

During his time as professional athlete, John earned several awards, including

- Paralympic Bronze Medal 100m at the Beijing Paralympic Games 2008
- IWASF World Champion 100m and 200m, International Amputee and Wheelchair Sports Federation, 2007
- Paralympic World Cup Champion 200m, and Silver Medallist 100m, International Paralympic Committee, 2007
- World Silver Medallist 100m and bronze Medallist 200m, International Paralympic Committee, 2006
- European Bronze Medallist 200m, International Paralympic Committee, 2005

In November 2022, John was selected as a member of the ESA astronaut reserve and to take part in ESA’s feasibility study “Fly!” to improve our understanding of, and overcome, the barriers space flight presents for astronauts with a physical disability.