Timothy Worthington is an Artisan Tailoring trainer located on Theramore Isle of Dustwallow Marsh.
In-game Picture
Location in Dustwallow Marsh
He is upstairs in a small building that is the first on the left after getting off the boat or arriving with the flight master. (see 2nd picture below)
Coordinates: 66.2, 51.6
TomTom command:
/way Dustwallow Marsh 66.2 51.6 Timothy Worthington