Great thread!
I believe I was one of the last students to pass through Galaxy (PPL & CPL theory). John was my instructor most days but Elizabeth did take me up occasionally.
I had the exact same experience with the mixture control!
I remember on one flight trying to locate an airstrip and finding I was just about overhead decided to join the curcuit and execute the required touch-and-go. JB had other ideas and grabbing the controls spiraled down and lined us up, then promptly hand back over to me. As we were already about half way down the strip I decided to go around and applied full power only to find the controls again fighting against me as JB pointed us downward. I'd had enough at this stage and refused to take the controls back as we were about to touch down with not much runway to spare.
We just made it over the fence at the end of the runway, I think even JB realised it was way too close. Once we were away again I took over and we headed home in silence. Elizabeth met us as we were taxiing in. She could see by the look on my face that all was not well and asked me what had happened. I told her and she promptly credited me back the cost of the hire. JB was sufficiently chasened.
It was the one and only time things got cranky and was fogotten quicky and we retired to the bar.
John and Elizabeth treated me like a son. I remember JB dancing with my dear old Grandma, he had some moves! I met some great pilots in that bar. Some of their stories about PNG led me to eventually make my own way up here, unfortunately not as a pilot.
Shortly after Elizabeth's death I left Australia. The turn out at her funeral was testament to her legacy. On my infrequent trips back home I called on John until one day the door was shut for good.
True characters both of them.