About Baldwin Trevilian, of Trevelyan
If the name is spelt as Trevelyan researchers are much less likely to find original historical documents for these men.
The name was most often spelt as Trevilian, Trevelian, Trevilion,Trevillian or very rarely Trevilyan. The family name was changed to Trevelyan (in one lineage) much later in the 17th century. No one used Trevelyan except the line of Sir George Trevelyan Baronet of the 17thC. Trevelyan was probably not used in this generation of Baldwin. There are no original source records of its use.
Trevelyan was adopted in modern times perhaps to distinguish themselves from all other Trevilians. It reflected the Celtic spelling perhaps to appeal to their local Cornish sense of nationalism that had begun to arise and suggest a pre-Norman origin as their coat of arms might suggest with the horse rising from the sea to carry the Trevelyan family founder to safety. When we see the Trevelyan spelling, it usually indicates something written in the 19th or 20th century.
Trevelyan is a Brythonic Celtic spelling, not Norman. After the Norman Conquest, the French spelling of the name was used for many centuries, such as Trevilion or Trevillian. It was a sign of status since Normans were in power.
Trevilian is proposed to be a descendant of Vyvyan, with the prefix TRE attached to indicate "from", which is the convention in Cornwall. Furthermore, they share the Lyonnesse legend. The Vyvians of Truro are derived by certain genealogists from one Vivianus Annius, a Roman general, son-in-law of Domitius Carbulo." Centuries later, a descendant of the Roman general served as a knight in King Arthur's court. (Quar. Rev. c. 11, p. 304.) Others consider the name to be from Cornish vyvyan means to flee. Polwhele, under chuT/vyan, " to escape, to fly," says. "Hence Vyvian, flying on a white horse from Lyonesse when it was inundated, is said to have derived his name. He was then governor of Lyonesse. The family of Vyvian gives a lion for its arms, and a white horse, ready caparisoned, for its crest, in memory of that incident." The Vyvyan word may derive from vy-vtariy the small water. (See Trevivion.) Vy vyan, Viuian, Vivin, Viven, Trevilian, Trevillian, Trevelyan are different orthographies of the name. "Tre" means "from". “ Trevyvyan might thus mean, fleeing from the water. -David Hillman