Jack Regan is a fictional character from the British television series The Sweeney, which aired in the 1970s. He is portrayed as a tough and dedicated detective in the Flying Squad, a branch of the Metropolitan Police Service in London. Regan is known for his no-nonsense approach to policing and often bends the rules to achieve justice. The character is played by actor John Thaw, who brought depth and charisma to the role. Jack Regan's adventures often involve tackling serious crimes, including armed robbery and organized crime, reflecting the gritty realities of law enforcement during that era.