Possible Clues:

• Nervous of having anything aged a century to stand on
• Fear or reluctance due to chilled extremities
• Reason to rethink, maybe
• Lack of courage
• A hundred years of age and twelve in more - that's enough to make one feel apprehensive
• To be so chilly by the yard is enough to make one nervous
• Loss of courage or confidence
• Carbon dated measures give loss of nerve
• Feeling of fear - in lower extremities?
• Eleventh-hour panic