Is there more to this than a leyenda negra inglesa?

"The last thing [King Philip of Spain] wanted was to go to war, particularly with the English, whose formidable spirit he knew from the days when he had been their king.
     "But the provocation had been continuous. . . . [And] Then there were the slave traders.  In accordance with his stern moral code Philip forbade his American colonists from enslaving the native Indians and from importing negroes.  They resented this, and readily bought from Hawkins, although trade of any kind was forbidden them except with their Mother Country.  Not only was [Queen]  Elizabeth cognizant of this contraband business, she was a partner in it.  She had lent a ship of her own, unsuitably called the Jesus, for this very purpose.  Bristol grew rich once more with the trade that St. Wulstan had suppressed there in the eleventh century.  English galleys, laden with human cargo, plied regularly between America and West Africa, and on their return journeys, as often as not, stopped to sack a Spanish outpost or board a treasure ship."

     Evelyn Waugh, Edmund Campion (London:  Longmans, Green and Co.,1937 [1935]), 105.  I merely note the claim.  It would be interesting to know what a specialist would say.