and destroyed Bletchingley Castle, whose owner Gilbert de Clare, Earl of Hertford and Gloucester, was de Montfort's most powerful ally. By the 14th century, castles were of dwindling military importance, but remained a mark of social prestige, leading to the construction of castles at Starborough near Lingfield by Lord Cobham, and at Betchworth by John Fitzalan, whose father had recently inherited the Earldom of Surrey. Though Reigate and Bletchingley remained modest settlements, the role of their castles as local centres for the two leading aristocratic interests in Surrey had enabled them to gain borough status by the early 13th century. As a result, they gained representation in Parliament when it became established towards the end of that century, alongside the more substantial urban settlements of Guildford and Southwark. Surrey's third sizeable town, Kingston, despite its size, borough status and historical association with the monarchy, did not gain parliamentary representation until 1832. Surrey had little political or economic significance in the Middle Ages. Its agricultural wealth was limited by the infertility of most of its soils, and it was not the main power-base of any important aristocratic family, nor the seat of a bishopric. The London suburb of Southwark was a major urban settlement, and the proximity of the capital boosted the wealth and population of the surrounding area, but urban development elsewhere was sapped by the overshadowing predominance of London and by the lack of direct access to the sea. Population pressure in the 12th and 13th centuries initiated the gradual clearing of the Weald, the forest spanning the borders of Surrey, Sussex and Kent, which had hitherto been left undeveloped due to the difficulty of farming on its heavy clay soil. Surrey's most significant source of prosperity in the later Middle Ages was the production of woollen cloth, which emerged during that period as England's main export industry. The county was an early centre of English textile manufacturing, benefiting from the presence of deposits of fuller's earth, the rare mineral composite important in the process of finishing cloth, around Reigate and Nutfield. The industry in Surrey was focused on Guildford, which gave its name to a variety of cloth, gilforte, which was exported widely across Europe and the Middle East and imitated by manufacturers elsewhere in Europe. However, as the English cloth industry expanded, Surrey was outstripped by other growing regions of production. Though Surrey was not the scene