In 1956, he was selected to represent Australia in the Melbourne Olympics, and he was forced to defer his studies. He won the 110 yd Queensland backstroke title before retaining his Australian title in Sydney. He joined the Australian team at the 12-week winter camp in Townsville, where he worked under the tutelage of Forbes Carlile. At the Townsville camp, Theile initially swam slower in the time trials than John Monckton and John Hayres, but eventually defeated them in the final time trials. At a later Brisbane event, he won again in 64.5 s, but Monckton defeated him in Sydney with a new record time of 63.3 s. However, Theile later struck back with a time of 62.9 s at the final trials in Melbourne, setting a new world record for long-course events.