Green’s Dictionary of Slang

1. a seven-shilling piece; thus used fig. for a pound.

1811		Lex. Balatronicum n.p.: Spangle. A seven shilling piece.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1900		Sporting Times 7 Apr. 1/3: Mildly protesting and much flurried, Charlie put down a ‘spangle’ by the side of the twopence; but he knew he had been done.
1905		A. Binstead Mop Fair 214: Samuel was occupied in raising twenty thousand spangles.

2. (US) an upper-class and/or rich individual.

1856

Life in Boston & N.Y. (Boston, MA) 22 Nov. n.p.: Messrs Murray and Holland [...] two ‘spangles,’ the former of whom captivated a Miss F— .

3. generic for money.

1879		‘’Arry on Crutches’ in Punch 3 May 201/1: This last lardy fashion, well there, – / It wouldn’t quite run to it, Charlie — I ’adn’t the spangles to spare.
1902		Times (Shreveport, LA) 12 May 3/5: His duty is to ‘mooch spangle’ (beg money) and ‘bat’ (knock at a door) for ‘dukies’ or ‘lumps’ (a lunch).