One of Gerry Anderson's only non-science fiction efforts, and his first since Crossroads to Crime (1960).
The lead role was originally named Craig Bradford and Chuck Connors was the first choice before Robert Vaughn was cast and the character renamed Harry Rule.
Character actor Nigel Green made one of his last appearances on TV when he was a guest star on "The Protectors." Not long after, this underrated actor died tragically in May 1972.
Robert Vaughn enjoyed spending time in England whilst making the series. He stated that London was a favourite city of his.
"The Protectors" was one of the last TV shows of its kind before British television was given a more gritty and naturalistic look.