Quillon was born in 1970 and grew up in the South West of England. He has been a Christian since 1979 and is married to Sandy. They have three children and the family has lived in Wallingford since 1993. Quillon works as a Principal Scientist at HR Wallingford, specialising in Hydroinformatics. He studied Mathematics at Brunel and Bath Universities.

Quillon plays the guitar and enjoys board games, history and archaeology. His wife Sandy works in the education sector, having also been a Staff Nurse at the Churchill Hospital in Oxford specialising in home dialysis. She is also musical and plays the piano, guitar and saxophone.