Green’s Dictionary of Slang

(Aus.) a morning coat.

1881		Bulletin (Sydney) 12 Mar. 4/3: Bonnor goes in for a horse-shoe pin and white vest, and has a pair of lavender 37’s stuffed into the breast pocket of his Bond-street ‘banger’.
1882		Sydney Sl. Dict. 10: The Parson is on the highfly in a fantail banger.
1886		Bulletin (Sydney) 13 Feb. 7/3: Behold the smart blue tie / The ‘two-ten’ fantail banger, and / The health-glow in his eye!
1904		Sydney Sportsman (Surry Hills, NSW) 9 Nov. 3/5: [He] took off his long-tailed banger [and] hung it on a peg near the door.
1914		Bulletin (Sydney) 26 Nov. 44/1: ‘Lownge, business, mornin’ or evenin’ wear?’ scoffs a bloke in a long banger, an’ smilin’ all over his horrid countenance. I was up to him. ‘One ov each,’ I chips, an’ winks.
1921		F. Grose A Rough Y.M. Bloke 26: Orl the people ’ad gorn orf the platform, orl bar one bloke with a long-tailed banger and shiny ’at.
1964		B. Hesling Dinkumization or Depommification 136: I still when wearing my long-tailed banger to fancy weddings have one link in rolled gold and the other in eighteen carat.
1978		D. Vawr Ratbag Mind 17: He left three of his old morning-coats (‘bangers’ in the slang of the day) hanging in a bedroom.