The Lord Chancellor of England is seated upon a woolsack because it was upon a woolsack that this fair land rose to prosperity.
The most remarkable body of traders in England during the Middle Ages were the Merchants of the Staple, who traded in wool.

The wool trade had for long been the largest and most lucrative body of trade in the country, and it was one in which the Kings of England were particularly interested, for their customs revenue was drawn largely from wool and wool fells; and, moreover, when they desired to borrow money in anticipation of revenue it was to the wool merchants that they turned, because the wool merchants were the wealthiest traders in the country.
For these and other reasons the Government adopted the custom of fixing staple towns, which acted as centres of distribution through which the export trade was forced to go.

The location of the Staple was altered from time to time; sometimes it was at Bruges, sometimes at Antwerp, sometimes in England; but usually it was at Calais, where it was first fixed in 1363 and finally established in 1423.

Through the Staple all wool and wool fells, hides, leather, and tin had to pass, and the organization of the system was complete when the body of wool merchants, in whose hands lay the bulk of the Staple trade, were finally incorporated in 1354, under the governance of a mayor.

The system was a convenient one for Crown and merchants alike.