Lord Warden of the Stannaries

The Lord Warden of the Stannaries (from for Tin, Sn) used to exercise judicial and military functions in Cornwall, in the United Kingdom, and is still the official who, upon the commission of the monarch or Duke of Cornwall for the time being, has the function of calling a stannary parliament of tinners. The last such parliament sat in 1753.
The first Lord Warden of the Stannaries of Cornwall and Devon was William de Wrotham, who was appointed during the reign of Richard I on 20 November 1197. Until 1502 normally separate Lords Warden were appointed for Cornwall and Devon (as shown in brackets below) and these also acted as stewards for Duchy estates in those counties. 
In 1502, Robert, 2nd Lord Willoughby de Broke was appointed as Lord Steward for Duchy estates in Cornwall and Devon, Lord Warden of the Stannaries in both, Master Forester of Dartmoor, and the successors appointed since have been granted these offices/titles. The current holder of the post is Nicholas Bacon.
A relevant Vice-Warden, frequently for one of the two counties for a warden who normally lived elsewhere, existed through many of the years 1386 to 1870. Other than being assigned roles connected to the occasional parliaments these had responsibilities as controller of the coinage and master of assay, working in concert with the Royal Mint which dominated high-value coinage end products through its jury system of trial of the Pyx.
Bibliography.
For list of Lords Steward and Lords Warden of the Stannaries in Cornwall and Devon, and Vice-Wardens of the Stannaries (1197–1965): 