Mathilde Vignes

 was the older sister of Victoire Vignes. The women came from a long line of cheesemakers. Their family were friends with the Doctor, going back several generations.

When Mathilde was eight, Victoire tried to run away from home, only to be caught by Mathilde.

At the age of eighteen, Victoire helped the Doctor save Earth from the Voltranons, while Mathilde stayed home to look after their mother.

When the two women were older, they parted ways. Mathilde stayed at the family home to make cheese the hands-on way, while Victoire went to Paris and used science and chemicals. Some of Victoire's cultures were stolen, and the Seventh Doctor and Inspector Toprak visited Mathilde to see if she had stolen them. She had stolen them, hoping to make a cheese that was immune to disease. (PROSE: Culture War)