Green’s Dictionary of Slang

1. a suit of clothes .

1930		(con. 1914–18) Brophy & Partridge Songs and Sl. of the British Soldier.
1936		J. Curtis Gilt Kid 16: ‘Yes,’ he said looking down on his striped suit with obvious pride, ‘this whistle I got on’s a bit different from the old grey one they dish you out with back in the queer place.’.
1938		L. Ortzen Down Donkey Row 148: I’ve jest bought a new whistle an’ flute.
1943		M. Harrison Reported Safe Arrival 11: Yer whistle, yer balmy date! Yer whistle-an’-flute.
1953		B. Behan Scarperer (1966) 78: Besides, the old whistle and flute he got, you wouldn’t be caught dead in.
1956		‘Charles Raven’ Und. Nights 164: He is a natty little geezer in a forty-guinea whistle.
1962		F. Norman Guntz 5: My rather threadbare civvy whistle felt rather cold.
1969		S.T. Kendall Up the Frog 20: ’E must be in the bees ’n’ honey cos ’es got [...] a new whistle ’n’ flute wiv a Peckham Rye to go wiv it an’ a fancy new Jim Prescott.
1975		‘P.B. Yuill’ Hazell and the Three-card Trick (1977) 117: Cor, Desp, that is a rascal of a whistle. It don’t fit you anywhere, do it?
1985		S. Berkoff West in Decadence and Other Plays (1985) 93: Not to spoil their whistles / crush their shoulder pads.
1992		I. Rankin Wolfman 68: A suit, you plonker. Whistle and flute, suit. Rhyming slang.
2001		K. Sampson Outlaws (ms.) 7: He wears [...] his Patrick Cox loafers and always a smart whistle.
2010		Metropolitan (Eurostar Mag.) Nov. 3: A Nice Whistle and Flute. Celebrating Savile Row.

2. (Aus.) in pl., boots.

1967

‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xliii 11/2: whistle and flutes: Boots.

3. cocaine [= toot n.¹ (4)].

2000

J.J. Connolly Layer Cake 12: We’ve got a Junior-Yuppie-Mafia thang going down, living the life, with JPG suits, Suzuki jeeps, Champagne and whistle all the way.