The first episode was filmed in the northern Wales village of Portmeirion. Patrick McGoohan would return here to film "The Prisoner" (1967).
Based on his success as John Drake, Patrick McGoohan became one of the first actors considered for the role of James Bond in Dr. No (1962). Between this series and the later "Danger Man" (1964), all the "regular" actors in the Bond movies - Bernard Lee, Lois Maxwell and Desmond Llewelyn- would guest star with McGoohan, as would many future Bond co-stars such as Honor Blackman and Zena Marshall to name just two.
The show resumed production with 60-minute episodes in 1964. It was renamed "Secret Agent" for American distribution.
Virtually identical in format and style to the later "Danger Man" (1964) with two major differences: John Drake is an American in this series, and episodes include narration.
John Drake says the phrase "I'm obliged" in virtually every episode; the catch phrase did not return in the later 1964 series.
In this early series, the character of John Drake is clearly defined as being an American. When the character returned for the second "Danger Man" (1964) series, the character had become either British or Irish (exactly which was never settled upon definitively).
Although hugely successful in Europe, this show failed to find an audience in American syndication and was cancelled after one season. By the time production resumed in 1964, the James Bond fad had hit and Americans were more receptive to the idea of a spy TV series.
Contrary to publicity surrounding this show's DVD release in 2003 that suggests this series was never shown in America, this early "Danger Man" series was indeed broadcast in the US in 1961, and under its original title.