Green’s Dictionary of Slang

‘CRANNY , s. In Bengal commonly used for a clerk writing English, and thence vulgarly applied generically to the East Indians, or half-caste class, from among whom English copyists are chiefly recruited’ (Hob.-Job.).

1841		F.J. Bellew ‘Memoirs of a Grffin’ in Asiatic Jrnl and Monthly Register 9 May 45: [We] passed through several rooms, one of them devoted to refreshments, and partly filled with gay Lotharios, some few military, the rest belonging to the orders 'shippy' and 'cranny,' and finally entered the ball-room.
1853		Delhi Sketch Bk 1 Nov. 74/1: The Loves of the Crannies [...] These three had once been officers, / Under the State as clerk or cranny [...] The first who spoke was one with look / Least Anglo-Indian.
1860		W.H. Russell My Diary in India 151: Simla has its ‘St. James’ and its ‘St. Giles’,’ and the latter is constituted by the tradespeople, and by the Crannies, or Kerannies, who are writers in the various offices, and are oftentimes Eurasians.
1876		J.W. Kaye Hist. Sepoy War III 32: From the less fashionable outskirts [...] occupied mainly by the great world of clerkdom - the so-called ‘crannies,’ official and commercial, of Calcutta - the exodus is described as universal.