Ash,
You are confusing two separate organisational aspects.
With respect to the RAF VR follow the link. You will find info relating to the status of UAS and DTUS unit staff and students in the vicinity.
Royal Air Force Volunteer Reserve - Wikipedia, the free encyclopedia
RAF Officers are in a Branch; Engineer, Logistics, General Duties etc.
Non-comissioned members of the RAF are in a Trade. For example there are 7 engineering & technical trades but only one Engineer Branch ie specialist worker bees and management. The question of ORs being 'Branch' or not is therefore illogical.
Riskman