Origen of Monteith-Menteith-and 30 variations
This surname; Monteith; Monteath; Montooth;and Menteith et.al; and it's many variations can be searched on this net by typing in on your browser page space; Thomas Menteith. While many of the items are about Menteiths, go to number 25 / about the Lake Menteith / Teith. In a 1234 A.D. Charter, the name was spelled Mynyteth, etc.
But what is of real interest is Item #27, The Earldom of Monteith. Here you will discover that the first Monteiths were two sons of Sir Walter Stewart, High something or other in Scotland, and that Sir John Menteith's name is held in infamy for his betrayal of the Scottish hero, Wallace. It doesn't say why they gave up the name Stewart for Menteith.
Now go to it. ELTON