Honorific title in the gift of the High-King and Emperor at the time of The Winterbough Saga.
This was not always so; prior to what is known in Elfhame as The Coming of the Skunks, the post was held by a roe-buck. It is not clear precisely how the Master was appointed at this time, whether it was the result of the Eldest selecting him, the roe-buck militia selecting him, or some combination. In any event, the Master was responsible for the defence of the Vale of Elfhame.
After the conquest of Elfhame by Irenaeus, the honour was held by the Crowns. It is not clear from The Winterbough Saga how many furs held the position between the conquest, and when Fumasgift Bowyer was appointed to the position by King Sartorius.
With the bankruptcy and madness of Bowyer (as a direct result of the events recounted in "Speaking Volumes"), the honour fell vacant, and remained vacant until it was awarded to Westersloe Winterbough V by King Alder Sartoriusson, most likely at the instigation of his younger brother, Marshal Roland Sartoriusson.
The post carried no right of remuneration, but it did carry with it the right to live at the Master's Lodge, a building just outside of Greytor-village. Initially a ruin at the time of Winterbough's accession, it was later restored at Imperial expense.
It is also revealed in a later adventure that the Mastership did carry with it certain rather unexpected rights, set forth in a Deed of Gift that had to be publicly proclaimed in the Vale. On a more practical level, the Master controlled the export of the Vale's most prized product, the persimmon brandy known as Three and a Half, which brought much gold to the Master's coffers. There was an unstated expectation that these monies would be used for the improvement and security of the Vale; Winterbough took this obligation seriously, and throughout many adventures can be seen so carrying out this intention.
There is one additional benefit to the post; at the public house known as The Sheaf of Arrows, there is a magickal chair, crafted before The Coming of the Skunks, that has plaques on the back listing all of the Masters before the Conquest, as well as Winterbough's name. The chair adjusted itself to fit Winterbough's size, and has been placed next to the fireplace in the common room of the inn.
It is implied that the post is not hereditary, though there was a certain expectation that a future High-King and Emperor would award the position to Westersloe Winterbough VI, should his father pass on or become unable to carry out the duties of the position.