Up until 2003, the RAF brevets were N (Navigator) E (Engineer) AE (Air Electonics Operator) AS (Air Signallar/Linguist) and LM (Loadmaster, including Helicopter Crewman). In 2003, the Airmen Aircrew sustainability study introduced the WSOp (Weapon System Operator) branch encompassing E,AE, AS, and LM branches with a single brevet (letters RAF with a crown). This was also the same brevet as the Weapon Systems Officers (Navigators).
Those who had qualified before 2003 were given the choice, most choose to wear the old brevets, though a few 'company men' adopted the new brevet.
The Australian Army wear a 'L' brevet for Loadmasters and an 'AT' brevet for groundcrew turned Air Technicians (Crew Chiefs).
The RAF also have a brevet for AT's, but only on a single type, and they are not commonly associated with the mainstream aircrew.
Hope this helps
MGD