It seems that:
Henry Spencer (b. 1353) married Isabel Lincoln (b. 1357)
They had at least two sons:
William Spencer (b. 1376) is the ancestor of Diana Spencer (b. 1961)
Thomas Spencer (b. 1378) is the ancestor of Susannah Spencer (b. 1680). Susannah married John Olin (b.1664) on October 4, 1708
You may recall that John Olin, who was once a 14-year old cabin boy as an indentured servant, forced into service on the British ship Man-O-War, jumped off the boat heading for Boston harbor. He swam ashore, stealthily traveled inland for about a week, and ended up in the care of the Narragansett Indians for eight years. He became an indentured servant to a Samuel Gorton until 1700, when he became a free man.
John and Susannah had four known children, Joseph, John, Henry and Eleanor. Joseph was the ancestor, eight generations back, of my mother-in-law. Thus my wife and daughter, if you go back far enough, have common ancestors with the guys who are second and third in line to the British throne.
This means, of course, that, as President of the Olin family reunion, New York/Pennsylvania branch, I ought to send the royals an invitation to the annual event.