Brockbank was the head of the Managing Director of the Mormon Pavilion at the New York World's Fair in 1964 and 1965. This pavilion majorly increased the amount of notice the church had in New York City and led to a major increase in the number of baptisms performed by the missionaries in the area. Brockbank was also involved with the later Mormon Pavilion at the 1970 World's Fair in Osaka, Japan. In 1973, Brockbank was called as president of the International Mission of the church, with responsibility for all areas where the church was not then organized. In 1975, Brockbank was among seven Assistants to the Quorum of the Twelve assigned to live outside the United States.