Oliver Hamilton was a brigadier teaching a Sandhurst Military School in the 1950s and spotted the potential of the "holy trinity" of cadets Walter Douglas, Leslie Johnston and Alistair Lethbridge-Stewart. He maintained a watchful eye over the career of the latter, and was instrumental in assigning Lethbridge-Stewart to the Scots Guards.
By the late 1960s, Major General Hamilton, now stationed at Army Strategic Command in Fugglestone, was Colonel Lethbridge-Stewart's commanding officer during the clean up following the London Event. (TV: The Web of Fear) He was aware of certain previous alien incursions, but could not support Lethbridge-Stewart's plan for assembling a special taskforce to deal with future alien invasions. He vetoed the idea of approaching the United Nations. He did, however, suggest to Lethbridge-Stewart that he would continue to work on High Command (British Army) while the colonel sought out further prove to support his position.