Indentured servitude was also practices in colonial America, which of course was part of England. The plight of indentured servants, after 1655, was worse than slaves.
Before 1655 all, black and white, were indentured servants, https://en.wikipedia.org/wiki/John_Casor
Slaves were considered property, and owners were careful of their property.
Indentured servants were not property, but were to be released after serving their contracted time.
The early colonists of means, the upper class, would pay for the transportation of persons, mostly indentured servants, and thus earned a headright of 50 acres for each person so transported, when ready they petitioned the king for a patent of 50 x number of persons transported.
Incidentally there were Irish slaves, as well as indentured servants, transported to Massachussetts and Virginia. https://www.amazon.com/Irish-Slaves-indenture-Contract-Immigrants/dp/145630612X/ref=sr_1_1?ie=UTF8&qid=1465653878&sr=8-1&keywords=irish+slaves
In the inventory of the estate of Richard Farrar of Perry County,Ala in 1860 (a 2nd cousin 4 times removed) mentions, among other property and slaves, a white male between the ages of 21 and 50.