Green’s Dictionary of Slang

1. (Aus.) a provincial dandy.

1882

A.J. Boyd Old Colonials 60: ‘The Nut,’ may be met with in all parts of Australia, but more particularly [...] in far-off inland bush townships [...] What is a Nut? [...] Imagine a long, lank, lantern-jawed, whiskerless, colonial youth [...] generally nineteen years of age, with a smooth face, destitute of all semblance of a crop of ‘grass,’ as he calls it in his vernacular.

2. a dandy, a very well-dressed, fashionable (if not overly intelligent) young man; occas. female nutess.

c.1900		[perf. Vesta Tilley] I’m Going to Be a Nut 🎵 With a little bit of fluff from the Chorus: / Can you see me? tut-tut / A bird and a bottle at the Ritz or Romano’s / What a nut, what a nut.
1904		in N&Q (1913) 26 July 78/1: I’m one of the nuts, one of the nibs .
1912		P.C. Wren Dew & Mildew 360: ‘Isn’t Buster a great old bird,’ murmured the Vice [...] ‘He's a Nut and a real Stout Fella’.
1912		Sport (Adelaide) 12 Oct. 13/3: They Say [...] That Next Sunday all the local K-nuts will march along [...] and sing comic songs.
1914		N.Z. Truth 31 Jan. 2/8: He is neither a ‘blood’ nor a ‘k-nut’.
1914		Bulletin (Sydney) 22 Oct. 10/4: The Official War Bureau describes a former ‘knut,’ [...] as performing his toilet in the morning in the open, washing his face in a saucepan balanced upon a petrol can, brushing his hair with an old nailbrush, and using the window of the car in which he had slept as a looking-glass.
1914		Laverton Mercury (WA) 31 Oct. 3/7: When the ‘nut’ enters a haberdasher’s shop and demands a high, white collar at the tie counter, he is referred to the collar assistant, and the tie man whispers to his colleague ‘apple-cutter,’ meaning that the customer wants to see some collars that will aggravate his Adam’s apple.
1914		Eve. Herald (Dublin) 21 July 2/5: Rhyming slang is on the increase [...] but I think the limit was reached the other day by a ‘nut’ who demanded of the lady behind the bar [...] ‘A Watebury Watch and a Major Loder’. The Hebe, who was undoubtedly a ‘nutess’ [...] provided him with a Scotch and Soda.
1914		Sport (Adelaide) 24 July 4/2: Two kernuts who have not seen their names in ‘Sport’ yet .
1915		Honk! 28 Jan. 2/1: Long hair on a ‘nut’ / Is excusable, but / On a soldier is simply infernal.
1915		Kipling ‘Sea Constables’ in Debits and Credits (1926) 26: Winchmore, the youngest, was more on the lines of the conventional pre-war ‘nut.’.
1916		G. Jennings Poached Eggs and Pearls (1917) 7: [to a woman] You’re a regular knut at the sink.
1916		Wipers Times 20 Mar. (2006) 42/2: Chumley Marchbanks, the knut of Bond Street.
1923		M. Garahan Stiffs 200: As Cherry said, we fairly had the bulge on the immaculately dressed ‘k-nuts,’ who so very definitely gave us the cold shoulder.
1924		Sun. Times (Perth) 6 July 11/4: The hot-sox Knuts and ill-clad flappers complete the inharmonious hashmagandy.
1929		(con. c.1910) J.B. Booth London Town 89: I’m Gilbert, the Filbert, / The Knut with a ‘K’ / The pride of Picadilly.
1929		J.B. Booth London Town 90: His dress clothes were the envy of the ‘nuts’.
1930		(con. 1914–18) Brophy & Partridge Songs and Sl. of the British Soldier.
1933		(con. WWI) F. Richards Old Soldiers Never Die (1964) 147: He was a nut. He was a proper Don Juan among the ladies.
1945		‘George Orwell’ ‘In Defence of P. G. Wodehouse’ in Coll. Essays III (1968) 350: Bertie [Wooster] is the ‘knut’ of the pre-1914 period, celebrated in such songs as ‘Gilbert the Filbert’ or ‘Reckless Reggie of the Regent’s Palace’.
1968		P. Barnes Ruling Class I ii: I’m Gilbert the Filbert the Knut with a ‘K’.
1999		N. Cohn Yes We have No 281: They call me the Knut from Kashmir.

3. see nut n.¹ (1b)