Company of Merchant Adventurers of London
The Company of Merchant Adventurers of London brought together London's leading overseas merchants in a regulated company, in the nature of a guild. Its members' main business was the export of cloth, especially white (undyed) broadcloth. This enabled them to import a large range of foreign goods.
The company received its royal charter from King Henry IV in 1407, but its roots may go back to the Fraternity of St. Thomas of Canterbury. It claimed to have liberties existing as early as 1216. The Duke of Brabant granted privileges and in return promised no fees to trading merchants. The company was chiefly chartered to the English merchants at Antwerp in 1305. This body may have included the Staplers, who exported raw wool, as well as the Merchant Adventurers. Henry IV's charter was in favor of the English merchants dwelling in Holland, Zeeland, Brabant, and Flanders. Other groups of merchants traded to different parts of northern Europe, including merchants dwelling in Prussia, Sconce, Sound, and the Hanse (whose election of a governor was approved by Richard II of England in 1391), and the English Merchants in Norway, Sweden and Denmark (who received a charter in 1408).
Under the Tudors 
Under Henry VII's charter of 1505, the company had a governor and 24 assistants. The members were trading capitalists. They were probably mostly composed of London mercers. The company also had members from York, Norwich, Exeter, Ipswich, Newcastle, Hull, and other places. The merchant adventurers of these towns were separate but affiliate bodies. The Society of Merchant Venturers of Bristol were a separate body, chartered by Edward VI in 1552.
Under Henry VII, the non-London merchants complained about restraint of trade. They had once traded freely with Spain, Portugal, France, Italy, and the Netherlands, but the London company was imposing a fine of £20, and drove them out of their markets. Henry VII required the fine to be reduced to 10 marks (£3.6.8 —- £1 = 3 English marks; 1 mark = 6s 8d). Conflict arose with the Merchants of the Staple, who sought to expand from exporting wool through Calais to exporting cloth to Flanders without having to become freemen of the Merchant Adventurers. The Merchant Adventurers kept control of their trade and Flanders as their port. Foreign merchants of the Hanseatic League had considerable privileges in England trade and competed with the Merchant Adventurers. These privileges were revoked by the English government in the mid-16th century.
The Merchant Adventurers had a commercial monopoly. Its members were the only persons entitled to export cloth from England. Their main market (or staple port) was Antwerp. When the King of Spain as sovereign of the Low Countries increased customs duty in 1560, the merchants began to have difficulty in Antwerp. This rise in duty conflicted with the treaty with Brabant of 1496. Three years later, the King of Spain prohibited English ships from coming to the Low Countries.
The Merchant Adventurers then decided to use other ports. Emden in East Friesland and Hamburg competed to entertain the Merchant Adventurers of England, who chose Emden. They soon found, however, that the port failed to attract sufficient merchants to buy the English merchants' wares. They left abruptly and returned to Antwerp. Operations there were interrupted by Elizabeth I of England's seizing Spanish treasure ships, which were conveying money to the Duke of Alva, governor of the Netherlands. although trade was resumed at Antwerp from 1573 to 1582, it ceased with the declining fortunes of that city.
Under the charter of 1564, the company's court consisted of a governor (elected annually was by members beyond the seas), his deputies, and 24 Assistants. Admission was by patrimony (being the son of a merchant, free of the company at the son's birth), service (apprenticeship to a member), redemption (purchase) or 'free gift'. By the time of the accession of James I in 1603, there were at least 200 members. Fees for admission were then gradually increased.
The conflict of the Merchant Adventurers with the Hanseatic League continued. The Hanse had the same rights in England as native merchants and better privileges abroad. They could thus undersell English merchants. Hamburg was a member of the League. When the English merchants left Emden, they tried to settle in Hamburg, but the League forced the city to expel them. Emden was tried again in 1579. The Emperor ordered the Count of East Friesland to expel the merchants, but he declined. The merchants remained there until 1587. In 1586, the Senate of Hamburg invited the Merchant Adventurers to return there, but negotiations over this broke down.
The merchants who had frequented Middelburg since 1582 were invited to return in 1587 to the (now independent) United Provinces. Due to impositions by Holland and Zeeland, this was an unpopular choice with company members. In 1611 the company's staple was permanently fixed at Hamburg. The Dutch staple port moved during the early 17th century from Middelburg to Delft in 1621, then to Rotterdam in 1635, then to Dordrecht in 1655.
The years between 1615 and 1689 were marked by periods, starting with the ill-fated Cockayne Project, when the company lost and then regained its monopolistic privileges. It moved its staple port from Delft to Rotterdam in the 1640s. The company suffered from trouble with interlopers, traders not free of the company who traded within its privileged area.
Hamburg Company 
When the Company of London lost its exclusive privileges following the Glorious Revolution of 1689, the admission fees were reduced to £2. After Parliament threw the trade open, the company continued to exist as a fellowship of merchants trading to Hamburg. Because they drove a considerable trade there, members were sometimes called the Hamburg Company. The Merchant Adventurers of London still existed at the beginning of the 19th century.
Further reading 
E. Lipson, The Economic History of England I (12th edition, 1959), 570-84; II (6th edition 1956), 196-269.