I know a MACR who was chopped by a commissioned MACR. He got a commission at the second attempt.
Remember the majority of AEOs were ex-AEOp or Signaller. I also met an ALM Sqn Ldr who was outstanding, an ALM wg cdr who was an outstanding pillock, and knew an AEOp NCO that made Air Cdre.
Many WSOp could have been WSO had the requirements been different when they were recruited.