If you are Theodore Tyler Pettus, we corresponded back in 1975. My wife saw your name on an advertisement in the New Yorker Magazine, and I tracked you down.
Portraits of the Norwich mayors are exhibited in St. Andrew's Hall (Blackfriar's Church) on Elm Hill (near Pettus House) in Norwich. I don't believe that there is an existing portrait of Thomas Pettus, mayor of Norwich in 1591; however, there is an excellent portrait of his son, Sir John Pettus, Knt., who was mayor in 1608.
Old St. Simon and St. Jude Church at the lower end of Elm Hill does have a monument to Thomas Pettus, mayor of Norwich in 1591. This monument has near life size statues of Thomas and his wife, Christian, and smaller ones of his sons and daughters. Presumably the second of those sons is Thomas Pettus, Jr. (mayor in 1614). He was the father of Col. Thomas Pettus, of the Virginia Council of State. The church is now closed, but the monuments were still there a few years ago, according to one of my correspondents.