Johnny Newcome and Johnny-come-lately are used interchangeably, except the former came first, popular in the early 1800s in England. The latter is an Americanised version from 1839—two years after the end of the Georgian era. An early 19th century Brit would have said “Johnny Newcome,” but a late 19th century American would have said “Johnny Comelately.” Now? Johnny-come-lately is used by both.

The term has several meanings, depending on the situation. It could refer to a newcomer, or it could be more nuanced, such as someone who arrives late but takes over as being superior, someone whose interest is faked, etc. Some great examples from Grammarist are the book club member who arrives halfway through the book discussion but claims to know everything only clearly never to have read the book, or the sports fan who only supports the team after they start winning.

The original usage is more controversial. It first appeared in 1808 in a series of satirical politicised cartoons, so contentious in its depiction of sailors in the West Indies that the cartoonist was convicted of libel.

Other satirists took up the torch and made follow-up pieces, such as William Elmes’ etchings in 1812. The term rose in popularity with continued publications, but the cartoons changed from political to comical, poking fun of youthful sailors in general, specifically the ones spending more time carousing and drinking than doing their duty for Crown and Country. Some notable ones include Thomas Rowlandson’s “The Military Adventures of Johnny Newcome” in 1815, the poem by Alfred Burton in 1818, and John Mitford’s illustrated poem “The Adventures of Johnny Newcome in the Navy” in 1819 satirizing Burton’s piece.

In the 1839 novel The Adventures of Harry Franco a character says, “But it’s Johnny Comelately, ain’t it, you?” thus changing the idiom for all history.