Pitmatic

Pitmatic (originally "pitmatical"), colloquially known as "yakka", is an English dialect used in Northumberland and Durham counties of England.
The separating dialectal development from other Northumbrian dialects, such as Geordie, is due to mineworker's jargon used in local coal pits. In Tyneside and Northumberland, "Cuddy" is an abbreviation of the name "Cuthbert" but in Durham Pitmatic "cuddy" denotes a horse, specifically a pit pony. In Lowland Scots, "cuddie" usually refers to a donkey or ass but may also denote a short, thick, strong horse.
According to the British Library, "Locals insist there are significant differences between Geordie [spoken in Newcastle upon Tyne] and several other local dialects, such as Pitmatic and Mackem. Pitmatic is the dialect of the former mining areas in County Durham and around Ashington to the north of Newcastle upon Tyne, while Mackem is used locally to refer to the dialect of the city of Sunderland and the surrounding urban area of Wearside". 
Nowadays, "Pitmatic" is an uncommon term in popular parlance. In recent times, all three dialects have converged and have acquired more features from Standard English. The dialect of English spoken in present-day County Durham is akin to Mackem, with the exception of Tees Valley areas whose dialect is closer to that of Middlesbrough.
Traditionally the dialect, with rural Northumbrian communities including Rothbury, used a guttural R. This is now less frequently heard; since the closure of the area's deep mines, younger people speak in local ways that do not usually include this characteristic. The guttural r sound can, however, still sometimes be detected amongst elderly populations in rural areas.
Dialectology.
While in theory pitmatic was spoken throughout the Great Northern Coalfield, from Ashington in Northumberland to Fishburn in County Durham, early references apply specifically to its use by miners especially from the Durham district (1873) and to its use in County Durham (1930). 
Dialect words in Northumberland and Tyneside, including many specific to the coal-mining industry, were collected in the two volumes of "Northumberland Words" by Oliver Heslop in 1892 and 1894.
Although he did not use the term, Alexander J. Ellis's work on the language of miners "between rivers Tyne and Wansbeck" has been studied as an early transcription of Pitmatic, which used informants from Earsdon and Backworth. In the 1950s, the Survey of English Dialects included Earsdon as a site and many of the forms recorded matched the transcriptions in Ellis's early work, although some appeared to have modified under pressure from other forms of English.
Harold Orton compiled a database of dialect forms for 35 locations in Northumberland and northern Durham, known as the "Orton Corpus".
In 1973, a book "Pit Talk in County Durham" was written by a local miner named David John Douglass, who later moved to South Yorkshire and published a series of socialist books.
In media.
Melvyn Bragg presented a programme on BBC Radio 4 about pitmatic as part of a series on regional dialects. Pitmatic has rarely featured in entertainment. One of the few cases is the second episode of Ken Loach's series "Days of Hope", which was filmed around Esh Winning in Durham with mostly local actors, although the lead Paul Copley has a Yorkshire accent.
Related forms of English.
Other Northern English dialects include