Cork is produced by a species of oak tree that thrives on sandy soil in the climate found around the west Mediterranean and the Portuguese coast. It is possible to strip the thick outer bark from a mature tree approximately once every decade. The bark then regenerates, its texture improving with each subsequent harvest for seven cycles, after which the quality declines.
The import book of 1698 at The National Archives shows 301 tons of cork being imported in that year, two-thirds of it arriving in English-owned ships and the bulk of it arriving in London. France, Spain and Portugal were the suppliers, with France contributing the major share. By 1719 more cork per capita was being imported and Portugal had taken the lead as our major supplier — a position which it maintained ever after.