White is educated in Belfast at St. John’s Primary School and St. Joseph’s Technical Secondary School. As a teenager he lives with foster parents. He wants to study medicine but financial circumstances prevented this. Between 1943 and 1965 he works for several Belfast tailoring firms and then as assistant manager of a Co-op department store. He marries Margaret “Peggy” Sarah Martin, another science fiction fan, in 1955 and the couple has three children. He later works for the aeroplane builders Short Brothers as a technical clerk, publicity assistant and publicity officer.
White becomes a science fiction fan in 1941, attracted particularly by the works of E. E. “Doc” Smith, which features good aliens as well as evil ones, and of Robert A. Heinlein, many of whose stories concern ordinary people. In 1947 he meets another Irish fan, Walt Willis, and the two help to produce the fan magazines Slant and Hyphen, which feature stories and articles by noted authors including John Brunner, A. Bertram Chandler and Bob Shaw. In 2004 both White and Willis are nominated for the retrospective Hugo Award for Best Fan Writer of 1953, although neither wins. White says that he started writing stories because the Slant team felt that Astounding Stories of Super-Science was too dominated by prophesies of nuclear doom, and his friends dared him to write the kind of story that they all liked to read. Getting published is fairly easy during the 1950s, as the World War II restrictions on paper are ended, and there are at least 12 science magazines in Britain and about 40 in the United States. His first published short story, Assisted Passage, a parody of 1950s Anglo-Australian emigration policies, appears in the January 1953 edition of the magazine New Worlds. Further stories appear in New Worlds during the next few years, but White’s attempt to access the more lucrative American market by submitting stories to Astounding Stories of Super-Science stall after the publication of The Scavengers. As a result, White’s work is little-known outside the UK until the 1960s.
In 1957, Ace Books publishes White’s first novel, The Secret Visitors, which includes locations in Northern Ireland. Ace Books’ science fiction editor, Donald A. Wollheim, thinks the original ending is too tame and suggests that White should insert an all-out space battle just after the climactic courtroom scene. In November of the same year New Worlds publishes White’s novella Sector General, and editor John Carnell requests more stories set in the same universe, founding the series for which White is known best. White gains a steady following for his scientifically accurate stories, which are examples of hard science fiction in New Worlds, despite the magazine’s promotion of literary New Wave science fiction during the 1960s.
White keeps his job with Short Brothers and writes in the evenings, as his stories do not make enough money for him to become a full-time author. In 1980 he teaches a literature course at a Belfast branch of the Workers’ Educational Association. When diabetes has severely impaired his eyesight, he takes early retirement in 1984 and relocates to the north County Antrim resort town of Portstewart, where he continues to write. For many years he is a Council Member of the British Science Fiction Association and, with Harry Harrison and Anne McCaffrey, a Patron of the Irish Science Fiction Association. He is also a strong pacifist.