John Grubb came from Cornwall in 1677 on the Kent and in 1679 settled at Upland (what is now Chester, Pennsylvania) and purchased land there. His son, Emanuel Grubb, was apparently the first male child to be born of English parents in the new colony of Pennsylvania. Emanuel and another son, John Grubb II (1684-1757) settled in Brandywine Hundred, in what was to be known as Grubb's Landing, and lived on "Stockton Plantation," a property of some 600 acres that would remain in the family possession for generations. Grubb's Landing was one of the first shipping points in New Castle County, Delaware, and was one of the points of access to the colonies by British ships during the American Revolution.

It is unclear if John Grubb was a Quaker or simply closely associated with Quaker families. After his death in 1708, John was buried at the St. Martin's Episcopal Church in Marcus Hook, Pennsylvania. The original St. Martins was built in 1700, although the current structure dates to 1845. The deed stipulates that no Quaker be buried there. While this may have been relaxed later, it is unlikely that John Grubb would have been interred at St. Martin's in 1708 had he been a Quaker. However, there is no record of John's religious views earlier in life. The Kent was chartered by William Penn and all of its passengers were either Quakers or closely associated with Quakers. John could only have learned about the Kent from a Quaker, and could only have been on the Kent if a Quaker vouched for him. But who could that have been?

Also on board the Kent was one Henry Grubb, an indentured servant, whose indenture agreement was signed in London on March 28, 1677, just before the Kent sailed. This Henry Grubb was the son of Wilmot Grubb of Stoke Climsland, Cornwall. The identity of Henry's mother was established by Gilbert Cope through Henry's 1695 will that named her as his mother and indicated that she was then living in Stoke Climsland. According to parish records, Wilmot Grubb, a Quaker, died in Stoke Climsland in 1696. However, Cope's guess concerning Wilmot's husband is probably wrong. Cope had access to a reference that recorded the imprisonment of Quaker's in England and he found the listing for a Henry Grubb of Stoke Climsland who was jailed in 1663. He wrote that this Henry was possibly Wilmot's husband. Note he used the word possibly, a fact that has been ignored ever since. The Stoke Climsland parish records fail to identify the name of Henry's wife. The only Wilmot Grubb listed was married to a Richard Grubb.

Wilmot Grubb was in London when the Kent sailed. Before Wilmot's son left on the Kent, he received a certificate of good conduct from the Ratcliffe Quaker Meeting. The Quaker archive at Swathmore College confirmed that the Ratcliffe Quaker Meeting was in London, which was one of the two points of embarkation for the settlers on the Kent. Wilmot signed Henry's certificate as his mother indicating that she was in London at the time.

John and Henry were probably related. It is highly plausible that John was on the Kent because he learned about the venture from Wilmot and she gave him a recommendation in London before the Kent sailed. This would appear to establish that Henry and John were somehow related, tying John to the Cornish Grubb family and probably to the Stoke Climsland area.

There is more collateral evidence that ties John Grubb to the Stoke Climsland area of Cornwall from one of his sons and from his granddaughter. Just who was the father of John Grubb and what was John's relationship to Henry Grubb remain questions for other researchers.