About half the champagne produced in France is exported to other countries. Still, the two biggest markets for the champagne industry are France and the United Kingdom — though both have been shrinking for years. Other foreign markets, including the U.S., Japan, and Australia, are growing. The Covid pandemic, as you can imagine, caused champagne sales in France and other markets to decline over the past two or three years. [
Link to source...]

Reims is just 160 kilometers (100 miles) from Paris — it can be a day trip.

This is the entrance to the caves (cellars) at the Pommery champagne house.
Pommery merged with the Belgian-owned Vranken wine group a few years ago.

Ay is a mystery to me. I have been to the village called Mareuil-sur-Ay, about 15 miles south of Reims, several times.
There's also a village called Fontaine-sur-Ay pronounced [ah-ee] (the H is silent). Normally when a town or
village is
sur (on) something, it's on a river or a stream. However, I can't find any trace
of a river or stream in the area bearing the name Ay.