Yong Thiam Joo John joined St Andrew’s Secondary NPCC Unit from 1974 to 1976. He was awarded the Best Cadet in 1975. In 1976, he was promoted to the rank of Staff Sgt. He completed NPCC Cadet Inspector’s Course (1st Batch) in 1977 and was seconded to St Andrew’s Secondary from 1977 to 1978. During his Cadet Inspector’s days, he had actively participated in various School Camping and Shooting activities organized by HQ NPCC, Police Academy. In addition, he had participated in National Parade and Youth Festival Parade.