Who is the old gypsy woman in Jane Eyre?

Chapter 17- 19 in the book says that there is an old gypsy lady at home. In fact, the old lady is pretending to be Rochester who is out.

Rochester went out and a gypsy wearing a headscarf came to the house. When it is Jane Eyre's turn to tell fortune, Jane Eyre discovers that this mysterious gypsy is Rochester, and he wants to test Jane Eyre's attitude towards him.