Green’s Dictionary of Slang

1. a fool, a gullible person.

1936		J. Curtis Gilt Kid 22: What with the steamer she’s got for regular and the odd ones she picks up she don’t do so bad, I should cocoa.
1943		J. Phelan Letters from the Big House 146: Rothschild was not only a mug – he was a prize steamer.
1954		J. Phelan Tramp at Anchor 31: Pipe that steamer.
1954		R. Fabian London After Dark 53: They call him, in thieves’ vernacular, ‘The Steamer’, which is rhyming slang that derives from ‘steam-tug’ and still signifies ‘Mug’.
1962		B. McGhee Cut and Run (1963) 79: Some of the hard men would consider me a bit of a ‘steamer’ as far as the old wife was concerned.
1977		D. Powis Signs of Crime 202: Steamer A mug or fool (Steam tug).
1981		(con. 1900–30) A. Harding in Samuel East End Und. 284: Steamer – Mug, fool.
1998		J. O’Connor Salesman 288: I made up me mind [...] I’ll give poor auld Homer one chance, I’ll go down and tell the poor auld miserable steamer a few good gags.
2002		(ref. to 1951) L. Pizzichini Dead Men’s Wages (2003) 112: Charlie did not visibly partake of the enthusiasm displayed by the steamers [...] preferring to stand apart, the disdain etched on his face.
2015		L. McInerney Glorious Heresies 93: [R]eady to tell me something else mind-blowing about the steamer on the screen.

2. (gay) a male homosexual, esp. the client of a male prostitute.

1960		S. Raven in Encounter Nov. n.p.: Wherever I look I see steamers [homosexuals prepared to pay boys money] and suckers .
1969		in M. Harris The Dilly Boys (1973) 57: He told me Stan is staying with a steamer in Notting Hill.
1972		B. Rodgers Queens’ Vernacular 118: the client; the one who pays for it. [...] steamer (Brit, fr rhyming sl steamer tug = mug = sap).
1973		M. Harris The Dilly Boys 69: I had responded to steamers who were warm and kind. But this steamer really got me down and I just knew I couldn’t go to bed with him.
1981		J. Weeks ‘Inverts, Perverts & Mary-Annes’ in Journal Homosexuality (1980/81) VI Fall/Winter 115: The clients of male prostitutes (the ‘steamers’ or ‘punters,’ ‘swells’ or ‘swanks’).
1991		(ref. to 1930s) in Porter & Weeks Between the Acts 138: There were the ‘steamers’ or punters themselves. That’s the old-fashioned term for them. I first heard it when I was about thirteen [i.e. 1930] and somebody said, oh he’s a steamer, he’ll give you half a crown, you see.
1996		P. Howard The Joy (2015) [ebook] [T]he public toilet on O’Connell Bridge used to attract a load of perverts and steamers to the area.
2000		P. Howard Miseducation of Ross O’Carroll-Kelly (2004) 53: Maybe he is a steamer [...] ‘I think they just talk about fashion and make-up.’ [Ibid.] 65: I’m sorry about telling your old pair you were a steamer.
2005		A. Lovejoy Acid Alex 237: I was placed in a dormitory with a bunch of steamers.
2010		W. Ings ‘Trolling the Beat to Working the Soob’ in Int’l Jrnl Lexicog. 23:1 64: [A] significant number of sparkle bogs (public toilets cruised during the day) might provide him with lunchtime steamers (men who paid for sex).
2019		P. Baker Fabulosa 298/1: steamer 1. a prostitute’s client, 2. a gay man who seeks passive partners.