Private Investigator was a groundbreaking British television drama that delved into the shadowy, complex world of private detection through the cases handled by an English detective agency. Central to the series was the character of John Unthank, played by seasoned actor Campbell Singer, whose understated but authoritative screen presence anchored the show. Unthank was supported by a capable team portrayed by Ursula Camm, Douglas Muir, Ian White, and Allan McClelland.