Green’s Dictionary of Slang

croakumshire n.

Northumberland.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Croakumshire, Northumberland, from the particular croaking in the pronunciation of the people of that county [...] where they are said to be born with a burr in their throats, which prevents their pronouncing the letter R.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1834		‘Jack Downing’ Andrew Jackson 99: Give the landers and croakumshires a bit of gig for their newspapers!
1890		York Herald 12 Apr. 12/5: The county of Northumberland itself is [...] known as Croakumshire.
1932		Dundee Eve. Teleg. 12 Dec. 9/4: ‘Croakumshire’ is Northumberland.