Alan Johnstone, farmer, legislator, and leader in public affairs, was born in Newberry, S.C. on August 12, 1849. He was born the son of Job and Amelia De Walt Johnstone. In his youth he was educated at Newberry Male Academy. Later he attended both Newberry College and the University of Virginia, but never received a degree on account of the chaos that the Civil War caused. Johnstone attempted to join the Confederate Army in 1865, but met returning soldiers in Greenville, S.C., after Lee's surrender.

Alan Johnstone was chosen as an elective member of the Clemson College Board of Trustees by the S.C. Legislature in 1890, and served in that capacity until 1894. In 1895 his peers elected him a life member. During his time as elective and life member, Johnstone was crucial in the establishment of Clemson College by his work on the building committee as well as help in establishing the Clemson College Agricultural Extension Service. He was elected Chairman of the Board of Trustees of Clemson College on August 21, 1907. Johnstone served in the South Carolina House of Representatives from 1907-1909, and in the South Carolina State Senate from 1909-1928.

Alan Johnston's work with the building committee at Clemson College highlights some of the difficulties that were posed by financial matters. The final completion of buildings and facilities at Clemson College were hampered by a lack of funds, and this issue threatened to derail the timetable that had been set for classes to convene. The problem was dealt with by providing convict labor to complete the unfinished work.

Alan Johnstone died on January 5, 1929 and is buried in the Johnstone graveyard in Newberry, S.C.