In this early series, the character of John Drake is clearly defined as being an American. When the character returned for the second Secret Agent (1964) series, the character had become either British or Irish (exactly which was never settled upon definitively).
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 Secret Agent (1964), three of the "regular" actors and actress in the Bond movies, Bernard Lee, Lois Maxwell, and Desmond Llewelyn, guest starred with McGoohan, as would many future Bond co-stars such as Honor Blackman and Zena Marshall to name just two.
In the series' opening title sequence, the shot of Washington, D.C. is a composite of the Washington Capitol in the background and the Castrol Building, complete with London Bus stop, in the Marylebone Road, London as the foreground. This building is now the residential Marathon House having been converted from offices to flats in 1998.
John Drake says the phrase "I'm obliged" in virtually every episode. The catchphrase did not return in the 1964 series.
Virtually identical in format and style to the later Secret Agent (1964) with two major differences: John Drake is an American in this series, and episodes include narration.