After the huge success of 'Department S', in which the character of Jason King had quickly become dominant, a spin-off series was developed called (not surprisingly) 'Jason King'.
King had left Department S and was working on his novels - the 'Mark Cain' stories. The rest of the cast of Department S did not appear at all, and were never mentioned.
The general premise for the show was that King wandered around the world living a playboy lifestyle and each week was somehow drawn into a crime which he neatly solved in time for the end credits. British Intelligence were often hounding him to work for them as a freelance which he generally resisted until they reminded him of his back-taxes. The series was made on location around Europe, in contrast to Department S which never left the back-lot at Pinewood.
Overall the series lacked much of the original sparkle and zest of Department S, the plots were much thinner and less original, and Wyngarde was becoming to old to play the part of a trend-setting playboy convincingly.
