A registrar is a doctor who is receiving advanced training in order to become a consultant. There are currently two registrars working at Holby ED. Registrars are required to wear scrubs while at work. These are generally a blue/green colour, although it may be a choice as Caleb Knight wore grey. This could be due to the fact that Ethan is a specialist registrar. Lily Chao wears what appear to be her own clothes.