The Privy Council was favorable to the company's proposition, and on March 13, 1663, the king instructed Lord Willoughby to permit the Spaniards to trade at Barbadoes for slaves notwithstanding any letters of marque that had been issued against them, or any provisions of the Navigation Act. He declared that the Spaniards were to be allowed to import into Barbadoes only the products of their own colonies, and were not to be permitted to carry away the produce of the English colonies. The effect of this provision was that in addition to slaves the Spaniards might obtain any products imported into Barbadoes from England.[66] The king settled the question of duties on slaves by ordering that ten pieces of eight on each Negro should be paid by all persons who exported slaves from Barbadoes or Jamaica to the Spanish colonies, except the agents of the Royal Company. The company was to pay no export duties on Negroes especially when the Spaniards had made previous contracts for them in England.[67]

Probably on account of the export duty on slaves which Willoughby had levied in 1662, the Spaniards were not anxious to return to Barbadoes. The company's factors therefore sent one of their ships with slaves to Terra Firma in order to convince the Spaniards that their desire for a Negro trade was genuine. On this occasion Lord Willoughby and the council of the island exacted £320 in customs from the factors. When the company heard of this procedure it immediately asked the king to enforce the order allowing it to export Negroes free of duty.[68] Thereupon the king ordered Willoughby to make immediate restitution of the £320 and to give the company's factors as much encouragement as possible.[69] Willoughby finally obeyed in a sullen manner. On May 20, 1665 he declared that the company had finally monopolized the Spanish trade for Negroes and that, because the king refused to permit an export duty to be levied on them, there was no revenue from that source.[70] The king's concessions to the Royal Company were of little avail, however, because the Anglo-Dutch war effectually stopped most of the company's trade in Negroes including that from Barbadoes to the Spanish colonies.

In considering the trade in slaves from Jamaica to the Spanish colonies it is well to keep in mind that this island lay far to the west of all other English possessions in the West Indies. It was located in the very midst of the Spanish possessions from which it had been wrested in 1655 by the expedition of Sir William Penn and Admiral Venables. The people of the island realized their isolation and occasionally attempted to break down the decrees of the Spanish government, which forbade its colonies to have any intercourse with foreigners. Although the English government began a somewhat similar policy with respect to its colonies in the Navigation Act of 1660, it was generally agreed that some exception should be made for the island of Jamaica in connection with the Spanish trade.

When Lord Windsor became governor of Jamaica in 1662 he was instructed to endeavor to secure a free commerce with the Spanish colonies. If the governors of the Spanish colonies refused to grant this trade voluntarily, Lord Windsor and the council of the island were given permission to compel the Spanish authorities to acquiesce by the use of force or any other means at their disposal.[71] Accordingly a letter embodying this request was written to the governors of Porto Rico and Santo Domingo, but unfavorable replies were received. In accordance with the king's instructions the Jamaica council determined to obtain a trade by force.[72] This was done by issuing letters of marque to privateers for the purpose of preying upon Spanish ships.[73]

In the following year, 1663, as has already been mentioned, Charles II commanded the governors of Barbadoes and Jamaica to permit the Spaniards to buy goods and Negroes in their respective islands, and to refrain from charging duties on these Negroes in case they were reexported by the agents of the Royal Adventurers.[74] This was followed by a royal order of April 29, 1663, commanding the governor to stop all hostile measures against the Spaniards. Sir Charles Lyttleton, the deputy governor, replied that he hoped the attempt to begin a trade with the Spaniards would be successful, especially in Negroes, which the Spaniards could not obtain more easily than in Jamaica.[75]

When Sir Charles Modyford became governor of Jamaica in 1664, the king repeated his desire to promote trade and correspondence with the Spanish plantations. Indeed Modyford's previous success in selling Negroes to the Spaniards probably influenced his appointment to this office. As soon as Modyford reached Jamaica he wrote a letter to the governor of Santo Domingo informing him that the king had ordered a cessation of hostilities and desired a peaceful commerce with the Spanish colonies.[76] Modyford instructed the two commissioners by whom the letter was sent to emphasize the trade in Negroes and to induce the Spaniards, if possible, to negotiate with him in regard to this matter.[77] Again the answer of the governor of Santo Domingo was unfavorable. He pointed out that it was not within his power to order a commerce with Jamaica, but that this was the province of the government in Spain. The governor, moreover, complained that the people of Jamaica had acted in the same hostile manner toward the Spaniards since the Restoration as they had in Cromwell's time, and therefore his people were little inclined to begin a trade with Jamaica.

The refusal of the Spanish governor to consider Modyford's proposition seemed all the more bitter since it was well known at that time that the Spaniards were obtaining many Negroes from the Dutch West India Company. The Genoese also had a contract with the Spaniards to deliver 24,500 Negroes in seven years nearly all of whom they expected to obtain from the Dutch at that "cursed little barren island" of Curaçao, as Sir Thomas Lynch called it. Lynch also observed that if the Royal Company desired to participate in the Spanish trade it would either have to sell to the Genoese or drive the Dutch out of Africa, because he did not believe it was possible to call in the privateers without the assistance of several men-of-war.[78] Just how much weight should be attached to this opinion is doubtful since Lynch was probably so much interested in continuing privateering against the Spaniards, that he cared little how much this would interfere with the company's attempt to develop the Negro trade.

Lynch's opinion was not shared by the king, who had heard that the privateers were continuing their hostilities against the Spaniards. He therefore informed Modyford that he could not adequately express his dissatisfaction at the daily complaints made by the Spaniards about the violence of ships said to belong to Jamaica. Modyford was strictly commanded to secure and punish any such offenders.[79] The governor issued a proclamation in accordance with the king's instructions,[80] and also notified the governor of Havana that offenders against Spanish commerce would hereafter be punished as pirates.[81]

After the Anglo-Dutch war began the company imported very few Negroes to Jamaica for the Spanish trade or for any other purpose. The king's stringent orders regarding privateers were gradually allowed to go unnoticed. Modyford again began to issue letters of marque, a procedure which naturally destroyed all possibility of commerce between the Spanish colonies and the Royal Company.

At the time the desultory trade in Negroes was being started with the Spaniards at Barbadoes, Richard White, of Spain, came to England as an agent for two Spaniards, Domingo Grillo and Ambrosio Lomoline.[82] These two men had been granted the assiento in Spain, that is, the privilege of furnishing the Spanish colonies with Negro slaves. In order to wrest some of this trade from the Dutch West India Company the Royal Company entered into a contract with White, in the year 1663, to furnish the Spanish assientists with 3,500 Negroes per year for a definite number of years. According to this contract the slaves were to be delivered to the vessels of the assientists in Barbadoes and Jamaica; one of the company's factors was to be placed on board such ships; and the necessary safe conducts were to be procured for their voyage to and from the port of Cadiz.[83] Sir Ellis Leighton, secretary of the Royal Adventurers, obtained permission for Grillo's agents to reside in Jamaica and Barbadoes.[84] Sir Martin Noell, one of the most important West Indian merchants, as well as a prominent member of the African Company, seems to have been intrusted with the collection of the money due on this contract.[85]