Sion Davies was an electrician credited on the following Doctor Who stories:
- The Doctor Falls
- The Eaters of Light
- Empress of Mars
- Extremis
- The Giggle
- Knock Knock
- The Lie of the Land
- Oxygen
- The Pilot
- The Pyramid at the End of the World
- The Return of Doctor Mysterio
- Smile
- The Star Beast
- Thin Ice
- Wild Blue Yonder
He is also credited as working as a Best boy on the following stories:
- 73 Yards
- Boom
- The Church on Ruby Road
- The Devil's Chord
- Dot and Bubble
- Empire of Death
- The Legend of Ruby Sunday
- Rogue
- Space Babies
In 2014, he started Sion Davies Electrical & Lighting Ltd, based out of Cardiff.