Possible Clues:

• Experienced hand getting on with little Timothy expressing hesitation
• Perhaps grandfather clock that's antique
• One has experience of an antique clock
• "Gramps"
• Rime told that's involved Ancient Mariner?
• Grandfather, one way or another?
• Experienced with an antique clock, it seems
• Grey figure played dim role around end of project
• An ex-con?
• Town historian, usually