Nancy is a guard's daughter who lived near the Skarloey Railway and sometimes polished the engines. On one occasion she was polishing Skarloey for Rheneas' return, and Duncan became extremely jealous after she had no time to clean him, as she was scheduled to help the Refreshment Lady that afternoon. She later appeared in "Very Old Engines" polishing Skarloey for his centenary. After he became cross and she called him a "crosspatch", Skarloey told her the story of his first days on the railway and the time he really was a crosspatch.
In the television series, Nancy only had speaking roles in the fourth season episode "Passengers and Polish", but made cameos in several seventh season episodes.
In the Railway Series, she has grown up and lives with her husband on the Isle of Man.
In the Sodor Island Fourm's "Extended Railway Series" thread, her father's name is Stanley.