 His remaining half-brother, Alexander, as the oldest surviving male, inherited the full rights to all of the estates – he became Sir Alexander Dunbar, 5th baronet of Northfield and Duffus.William probably could have expected assistance from his father in making his way in Britain, but not from a half-brother with whom he had never really been close.In the spring of 1771, William Dunbar sailed from London to Philadelphia to try his luck in America.