As requested below a few photos of the unique group of altars found along the Antonine wall at Auchendavy.
The group of five altars all dedicated by Marcus Cocceius Firmus. The one on the far right is the one to the Spirit of Britain and next to that is the one that mentions Epona.
Altar to various deities including Mars and Epona
Close up of the inscription of the altar mentioning Epona
Close up of the unique altar to the Spirit of Britain