He was known for playing both "tough guy" roles and authority figures, and is remembered for his portrayal of detective George Bulman between 1976 and 1987 in the popular Granada Television police drama series The XYY Man, Strangers, and Bulman, as priest Frank Kane in BBC drama The Paradise Club (1989–90), and as General Taggi in the first Star Wars film (1977).

[3] Henderson was born into a working-class family in Leytonstone, Essex, the son of a carpenter, and grew up in Epping.

After completing his national service as a technician in the Royal Army Dental Corps, he served with Essex Constabulary, reaching the rank of detective sergeant in their CID, and worked as an insurance salesman.

He did not become a professional actor until his thirties, when a friend dared him to audition for the Royal Shakespeare Company, with whom he subsequently performed from 1966 until 1972, going on to play many leading roles.

Henderson had two children, a son and a daughter, with his first wife Hilary, who died from a mysterious lung disease in 1977.