The New Yorker is a veritable fount of Britishisms. I have already written about the magazine’s propensity for the participial had got (instead of gotten), which, if anything, has got more pronounced over the years. I still remember the thrill of seeing–in a 2003 Janet Malcolm piece about Gertrude Stein–a sentence that began, “She and Toklas were about to move house from Bilignin to a manor in Culoz, a few miles away…”: move house being a Britishism (equivalent to Americans’ move) I had not seen before that and have not encountered since.
Alas, Eustace Tilley has slipped. In an April 11, 2011, profile of Wall Street Journal editor Robert Thomson, Ken Auletta refers to a Journal piece about Goldman Sachs “which was intended to be a twenty-five-hundred-word front-page leader.” I am fairly confident it was intended to be nothing of the sort. What James Brander Mathews wrote in his book Americanisms & Briticisms in 1892 still holds today: “An American‥calls that an ‘editorial’ which the Englishman calls a ‘leader’.” It is derived from the older term leading article, which is still in currency in the U.K. The Goldman Sachs piece was surely not an editorial–that is, an unsigned expression of the newspaper or magazine’s collective opinion–but what Americans would call a lead article: the featured report on the front page.
notoneoffbritishisms.com 
Might this not have been merely a case of American journo jargon–“lead article” becoming “leader”–not an attempt (conscious or not) at a Briticism?
Journo jargon combined with desire to seem cool.