Yan Tan Tethera

Yan Tan Tethera is a sheep-counting system traditionally used by shepherds in Northern England and some other parts of Britain. The words are numbers taken from Brythonic Celtic languages such as Cumbric which had died out in most of Northern England by the sixth century, but they were commonly used for sheep counting and counting stitches in knitting until the Industrial Revolution, especially in the fells of the Lake District. 

Though most of these number systems fell out of use by the turn of the 20th century, some are still in use. Curiously, the exact pronounciation even varies within counties.

(Taken from Wikipedia) 

Now compare that to the original Celtic languages:

Curiously, I remember once being told by my languages teacher at school - the late great Cornish language revivalist and folk singer Richard Gendall - that when he was a child growing up in Penzance in the 1930s he would hear fishermen at Mousehole and Newlyn counting crates of fish in Cornish.

As you can see from the above table, the origins of Yan Tan Tethera are easy to spot.

And I can't leave this subject without an appearance by the equally late and great Jake Thackray: