I have a brass check/token/tally (see above), which is of the same general style as those used in the collieries, but is labelled "ECLP Gothers" with a stamped number. It is 35 mm in diameter, uniface with a milled type edge. Gothers was the site of a china clay pit near St. Dennis in Cornwall. 

The initials "ECLP" stands for "English Clays Lovering Pochin",. This major Cornish clay producing company was formed from the amalgamation of many smaller clay producers in the early 1930s.  "Gothers" is the name of one of the company's many clay pits. This is the only check that I've come across relating to the Cornish China clay industry, not that I'm particularly a collector of them, and I wondered if any of the keener collectors have any, as there seems to be an interesting story of the use of the check I have. 

The Cornish clay pits don't have any underground workings (unlike the Devon ball clay ones) and so checks were not issued for the usual purpose of controlling and monitoring the movements of men into and out of the underground workings. 

I'm a member of the China Clay History Society and enquired of a few people I knew at Wheal Martyn China Clay Museum. The explanation that I had (from John Tonkin, who I know very well) was that he'd heard from an old chap that these discs were issued to German POWs who had elected to stay in England for a while after the war on reconstruction work. These POWs were assigned to E.C.L.P. who put them to work on building "Cornish units" - pre-fabricated houses made from china clay waste that earned E.C.L.P. a lot of money in the years following the war. Unfortunately many of the houses are now in a bad state and it is virtually impossible to get a mortgage on one. There are thousands of them in the West Country. There isn't much that John Tonkin doesn't know about the china clay industry, having worked in it for much of his life, and he is at a loss to come up with any other explanation for the checks. 

Any further information would be gratefully received!