Green’s Dictionary of Slang

la-di-da(h) n.1

also lad-dee-dah, la de da(h), lah-de-dah, lar-di-da, lardy dah, lardidardy, laudy-daw
[la-di-da(h) adj. (1)]

1. a snob; a member of the upper classes.

[UK]Man about Town 9 Oct. 36/3: I was pleased to see the abode of my friends the Lardidardies, who are living in great discomfort at the back, still hermetically sealed.
[US] ‘I Never Drink Behind the Bar’ in L. Levy Flashes of Merriment (1971) 280: Oh, your [sic] a lally cooler, Pete, a reg’lar la-di-da.
[UK]Bristol Magpie 15 Feb. 13/1: Scene A well-known city bar. Three ‘Lah-di-dahs’ doing their matutinal cigarettes and ‘bittaws,’ ogling and chaffing the barmaid [etc].
[Aus]Coburg Leader (Vic.) 19 Oct. 4/2: He is an awful toffy bloke / A lardy dah you know.
[UK]Rollit & LeBrunn [perf. Marie Lloyd] Hulloa, Huilloa, Hulloa 🎵 But yesterday I saw her - a perfect ladidah / Careering down New Bond Street in her Victoria.
[Ire]P.W. Joyce Eng. As We Speak It In Ireland (1979) 282: Laudy-daw; a pretentious fellow that sets up to be a great swell.
[UK]T. Burke Limehouse Nights 240: He [...] stood back, only mildly interested in the lah-de-dah.
[Aus] (?) H. Lawson ‘A Wet Camp’ in Roderick (1972) 894: I’ve seen one of them fancy fisherman la-di-dahs down there by the river shoot a bird like a curlew and break its leg.
[US]Hecht & MacArthur Front Page Act II: If you want me you’ll have to take me as I am instead of trying to turn me into some lah de dah with a cane!
[Aus](con. WWI) L. Mann Flesh in Armour 146: ‘Haw, haw, Constantia, some la de da’.
[UK]I. & P. Opie Lore and Lang. of Schoolchildren (1977) 75: Toff, swell, snob, nob, big-wig, lord, or la-di-dah.
[SA]C. Hope Ducktails in Gray Theatre Two (1981) 46: Vreks. ’s what I call them ... students and clerks and fancy-pants, la-di-das and cops and toecap sandals, khaki shorts and short back and sides ... they’re always against the jollers.
[UK]P. Reading 5x5x5x5x5 3v: Posh puff clever shite / La-de-fuckin-da.

2. (also lardidaism) snobbishness, affectation; upper-class and/or wealthy hedonism.

[Aus]Bulletin (Sydney) 7 Feb. 6/1: Tottles’ assumption of refined elegance, with a sort of lardidaism is ‘immence,’ but nothing can exceed his reproof of Bung for his vulgarisms and mispronunciation.
[US]Nat. Police Gaz. (NY) 24 Nov. 6/3: An elegantly dressed young man with much of the ‘la-de-dah,’ not to say ‘dude,’ about him.
[UK] in G.D. Atkin House Scraps 166: The young ’un goes to music-halls, / And does the la-di-da; / We are a shiney family, We are! we are! we are!
[Aus]W.S. Walker In the Blood 170: ‘Let’s go an’ ’ave a stroll in ’Yde Park,’ said Ted to Toby. ‘Do the lar-di-da a bit.’.
[US]A.H. Lewis Boss 253: [He] relapsed into his customary attitude of moral, mental Lah-de-dah.
[UK]J. Ware Passing Eng. of the Victorian Era 165/1: La-di-da (Street). Elegant leisure, and liberal expenditure.
[NZ]‘Anzac’ On the Anzac Trail 159: Officers (Navy) very fine fellows [...] No side or laddy-da .
[UK]M. Harrison Reported Safe Arrival 32: A ole sojer like Smudge, ’oo wz brought up proper, wiv no fancy lad-dee-dah.
[Aus]‘Nino Culotta’ Cop This Lot 216: So a coupla blokes come back from Italy or wherever they bloody been an’ bung on the lah-de-dah.

3. (US) an attractive girl or woman.

[US]Nat. Police Gaz. (NY) 21 Aug. 7/4: A nicely dressed young lady of about eighteen summers [...] walked leisurely down Howard street the other morning [...] She was what a Charles street dude would call a ‘daisy’ or a ‘lah-de-dah’.

In phrases

do the la-di-da(h) (v.)

(Aus./UK) to parade or otherwise act ostentatiously.

[Aus]Bulletin (Sydney) 16 Apr. 9/3: He was doing the lardy-de-dah on Coogee beach, surrounded by a bevy of fair ones, to whom he was imparting pleasing little fictions about the wealth of his relations.
[UK]Bristol Magpie 16 Nov. 10/1: The motley throngs of youthful promenaders, who are wont to do the ‘la-di-da’ in Whiteladies’ Road on Sunday evenings.
[UK]E. Powel [perf. Charles Coborn] ‘Four Fingers and a Thumb’ 🎵 He does the lardy-dah, picks a half-a-crown cigar / With his four jewelled fingers and a thumb.
H. Champion ‘The End of My Cigar’ [monologue] That’s the end of my old cigar [...] I’ve kept it now for twenty years to do the la-di-da.
[Aus]Sport (Adelaide) 10 July 4/7: Florrie R., the Balak tart, / Was doing the La-de-da .