Cau was elected mayor of Tilloy-lez-Marchiennes on March 15, 2020, with the entire municipal council also being members of her electoral list, and was inaugurated in May of that year following a long delay due to the COVID-19 pandemic, becoming the first known openly transgender mayor in France.
[2][3] She garnered international media coverage[4] and congratulations from French gender equality minister Marlene Schiappa, SOS Homophobie co-president Veronique Godet, and Giovanna Rincon [fr], head of the transgender rights group Acceptess-T [fr].
[2] Cau ran on a platform of developing social and environmental policies, particularly sustainable agriculture.
[2][3][5] As mayor, she secured repairs to the section of the historical Paris-Roubaix route (now part of the RD81) which crosses the village,[6] and other infrastructure improvements.
[8] Cau was born in Roubaix[4] and at the time of her election had lived in Tilloy-lez-Marchiennes for 20 years.