Green’s Dictionary of Slang

(Scot.) a thief; latterly a street thug, esp. from Glasgow.

1865		Leaves from Diary of Celebrated Burglar 76/2: Wattie ‘tumbled’ the ‘moll;’ ‘beef’ was given and half a dozen voices joined in the cry of ‘haud the keely’ (thief).
1889		Edinburgh Eve. News 23 Sept. 2/4: The defender [...] called him a ‘Glasgow keelie’ and a ‘prig’.
1890		York Herald 12 Apr. 12/5: A man of Glasgow is a Glasgow keelie.
1902		Manchester Courier 5 Dec. 14/7: The Glaswegians are ‘Keelies’.
1923		Dundee Courier 1 May 4/2: He’s veesited the Clyde / [...] / An’ heard the keelie chaff a loon / That bragged about Deeside.
1935		A.J. Pollock Und. Speaks n.p.: Keeler, a thief who robs drunken persons.
1935		G. Blake Shipbuilders (1954) 133: Most unbearable of all was the knowledge that he had fathered a waster, a work-shy, a keelie.
1944		Eve. Teleg. (Dundee) 26 Dec. 3/4: Monty [...] the Glasgow ‘Keelie’.
1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 111: In the Gorbals district of Glasgow precocious little keelies joyfully chorus to the tune their forebears took to the trenches long ago.
1979		J. Morrow Confessions of Proinsias O’Toole 30: She was to support the instant-propaganda theory that Meehaul had been gunned down by a duck-squad of Cameronian keelies.
1993		I. Welsh Trainspotting 205: Gles-kay-hee-lay-thit-ye-ur.