Patrick George Parsons, born with a unique name, spent a portion of his childhood in India with his uncle, an experience that likely had a lasting impact on his life. Later, he was sent to Christ's Hospital, a renowned charity school in England, where he formed a close bond with a fellow student, the future film star, Michael Wilding, who would go on to have a successful career in the entertainment industry. Some individuals even believed that Holt was the more talented actor of the two. After completing his education, Holt began his career in repertory theatres, and in 1939, he landed a leading role on the London stage. However, his venture into the world of stage acting was cut short when World War II broke out, and he was forced to join the army. During his time in the military, Holt saw service in various locations, including Burma, Singapore, and India, often undertaking secret missions behind enemy lines. By the end of the war, he had risen to the rank of lieutenant colonel.
After the war, Holt joined the J. Arthur Rank charm school and established himself as a leading actor of the 1950s second features, earning the nickname "the Dennis Price of B-films" from the renowned film critic, Stephen Quinlan. As he evolved into a character actor, Holt continued his career well into old age, working on stage, television, and in the cinema. He was still listed in the Spotlight casting directory at the time of his death. Holt's personal life was marked by two marriages, first to the actress Sonia Holm, and then to Sandra Dorne, with whom he occasionally co-starred. His marriage to Sandra was particularly happy, and Holt was devastated by her death on Christmas Day, 1992, an event that reportedly left a lasting impact on him.