Is there a place to store luggage securely at or new Vernon train station?
There is no left luggage or lockers or anything at the train station, according to SNCF's Gares et Connexions website.
You might check NannyBag or Stashr or one of those websites. I am sure some businesses around there take bags for a fee.
The Café-Tabac de la Gare used to but no more apparently. The Garden specifically says no. If you are coming by train is it possible to leave the luggage at your originating station or somewhere in that town? Nannybag has a facility but closed on Sunday and Monday.