Green’s Dictionary of Slang

out of date, old-fashioned.

1911		A. Quiller-Couch Brother Copas 78: Men have [...] put it, with like doctrines, silently aside in disgust. So it has happened with Satan and his fork: they have become ‘old hat’ [OED].
1918		Dial (Boston, MA) 64 391: We might as well admit that as talk this is ‘old hat’—like everything else we hear in ‘plays with a purpose’.
1938		W. Winchell On Broadway 17 May [synd. col.] The wordage has become distressingly old hat.
1948		(con. 1944) N. Mailer Naked and Dead 343: Isn’t this distrust of the bourgeois intellectual a little old-hat?
1952		Lait & Mortimer USA Confidential 164: Sex per se is passé in Los Angeles. Sex and non-virgin clubs, startling in other towns, are old hat here.
1962		M.K. Joseph Pound of Saffron 245: Brendan’s a good teacher [...] but he’s terribly old hat really.
1972		P. Fordham Inside the Und. 30: [This] strikes him as so old hat he has difficulty being civil.
1986		F. Taylor Auf Wiedersehen Pet Two 225: The Costa del Crime’s old hat now.
1999		K. Sampson Powder 440: Could’ve had untold Sister Acts, but it’s old hat an’ that, that, innit?
2000		Indep. on Sun. Real Life 16 Jan. 4: I know that a lot of club runners [...] think that London is old hat, a spent thrill.
2022		J. Hannaham Didn’t Nobody Give a Shit 153: Probably everybody's car sounded like that now; the technology was old hat years ago.
2024		J. Meades Empty Wigs (t/s) 270: ...then one day... pshaw... it feels like it’s old hat... you grow out of it.