Green’s Dictionary of Slang

a braggart, a show-off.

1837		‘Nights At Sea’ in Bentley’s Misc. June 625: There used to be a lot of outrageous tarnation swankers meet there for a night’s spree.
1889–90		Barrère & Leland Dict. of Sl., Jargon and Cant.
1905		Sporting Times 4 Mar. 1/5: The junior office-boy observed to the downy swank [etc].
1910		‘Doss Chiderdoss’ ‘The Sweetshop Girl’ Sporting Times 5 Mar. 1/4: Sometimes Gussy is a swanker, and he prates about his banker / To look lofty in the sweetshop girlie’s eyes.
1916		J.N. Hall Kitchener’s Mob 69: I pronounced the name [i.e. Ypres] French fashion which put me under suspicion as a ‘swanker.’.
1919		Marvel 1 Mar. 5: I’m betting Pye the Swank of England [...] that the zoozy Zanutis don’t hash Dimcox.
1929		J.B. Priestley Good Companions 191: Thought he was a little swanker.
1938		G. Kersh Night and the City 105: Ha! Blasted little swanker.
1940		M. Marples Public School Slang 59: Boys in general have a great flair for derogatory and vituperative expression [...] swot, swank, sneak, jew, swine, tick, scoff, cad, blog, nip, oik, lout, wet, drip, squit, squirt, mug, scug, sap, simp, seet, gump, muff, goof, goop, waft.
1950		A. Buckeridge Jennings Goes To School 216: You’re just a swank.
1958		Willans & Searle Complete Molesworth (1985) 197: He is a swank.