Date: August 23, 2021 12:34AM
...He was called to the First Presidency as a third counselor to church president David O. McKay on June 22, 1961. He was called as Second Counselor in the First Presidency on October 12, 1961, upon the death of First Counselor J. Reuben Clark. He was later called as First Counselor in 1963 to replace Henry D. Moyle, who had died.
After McKay died on January 18, 1970, Brown was not retained as a counselor in the First Presidency by the new church president, Joseph Fielding Smith. Never before in the 20th century had a new president of the church not called a surviving member of the previous First Presidency as a counselor. Brown returned as a member of the Quorum of the Twelve Apostles, where he remained until his death.https://en.m.wikipedia.org/wiki/Hugh_B._Brown
...By 1968, the First Presidency was composed of six members, larger than it had been at the death of Brigham Young in 1877. McKay's counselors in the First Presidency were Stephen L Richards (First Counselor, 1951–59); J. Reuben Clark, Jr. (Second Counselor (1951–59, First Counselor 1959–61); Henry D. Moyle (Second Counselor 1959–61, First Counselor 1961–63); Hugh B. Brown (Third Counselor 1961, Second Counselor 1961–63, First Counselor 1963–70); N. Eldon Tanner (Second Counselor, 1963–70); Thorpe B. Isaacson (Counselor, 1965–70); Joseph Fielding Smith (Counselor, 1965–70); Alvin R. Dyer (Counselor, 1968–70).