This was the consequence of being stung by a Hornet. She was slowly becoming possessed by them. In one performance where the Doctor was present, she exited while dancing and headed for the pier where she was keen to jump into the waves. The Doctor managed to save her and persuaded her to give the shoes back to the curatress.
She complied, but was shocked to discover that Mrs Wibbsey was possessed by the insect and reduced both her and the Doctor to two inches tall. They were placed in the garden of a quaint Victorian doll house. Inside, they watched as Peg Dolls came to life before them and chased them through the house. With the help of the Doctor, they managed to escape through a window.
Under the command of the Hornets, she was forced to put the shoes back on and was paraded down the streets, her mind being consumed by the Hornets as she was tortured into dancing. Using his scarf, the Doctor tripped her up, and Reverend Small removed the shoes from her feet. Her mind was never consumed. (AUDIO: The Dead Shoes)
The Doctor later discovered that Ernestina was still carrying the dormant Hornets inside her, who then made contact with her grandson, Percy Noggins, the taxidermist who cooperated with the Hornets in their scheme to control stuffed animals. (AUDIO: A Sting in the Tale)