Dictionary

Gentleman Jim en · NOUN

Possibly from the nickname of champion American boxer James J. Corbett (1866–1933) or American country music singer Jim Reeves (1923-1964).

(informal, uncountable, usually) A man, especially one named James, whose behavior shows him to have a polite, courteous, and respectable nature.
- When Sullivan met Corbett at New Orleans, Gentleman Jim landed the champion a terrific jolt with his right, smiled sweetly and said, "To think, John, of your coming all the way from Boston to get that." 1916, Elbert Hubbard, “Philip D. Armour”, in Little Journeys Vol. 11: Great Businessmen:
- Mr. McCrery … was headed for defeat until his opponent, a state legislator named Foster Campbell, was injured in a car crash. Mr. McCrery pulled his advertising and became known as "Gentleman Jim," a label that fit a personality his consultants had tried in vain to revamp. 2005 February 22, Sheryl Gay Stolberg, “In Eye of Social Security Storm, Quiet Power Broker Is Courted”, in New York Times, retrieved 16 Jan 2016:
- Lewthwaite . . . was also regarded as ultra-reliable in defence, as well as a consummate sportsman, often referred to as "Gentleman Jim". 2007 January 14, Dave Hadfield, “Obituaries: Jim Lewthwaite, Rugby league record-breaker”, in Independent, UK, retrieved 16 Jan 2016:
- Something puzzling: there were two Gentleman Jims in 71 Squadron. 1982, Vernon Haugland, The Eagles' War: the Saga of the Eagle Squadron Pilots, 1940-1945, →ISBN, page 93:

Spelling	Features	Labels	Source
Gentleman Jims	Number=Plur		lexicographic
Gentlemen Jims	Number=Plur		lexicographic