1961 - 63 years ago, and the
proper Avengers are featured in the cover to the TVTimes
This was from the first series of the show, when it was a 'serious spy programme', and the main character was Dr David Keel (Ian Hendry), with John Steed being a shadowy person who was very much in the background
The episode being promoted here was episode 10 - 'Hunt The Man Down' - which is one of many that is currently missing from the archives