The painting would likely have been displayed on the wall of a shop, such as a Drug Store or perhaps a Postal Office, or Government building of some kind. A Coat of Arms displayed on a coach or a train would be painted on a panel of wood or hardboard then heavily varnished for protection against the elements.
These rectangular paintings of the Royal Arms should not be confused with hatchments. The hatchment was originally displayed over the front door of the house of a dead person, whose arms it portrayed, and remained there until the deceased person was buried in the local church, whence it was then conveyed and hung on the wall of the nave aisle until a tomb or monument was erected. Fortunately, many of these hatchments were not removed after the tomb was made and can still be seen as large lozenge-shaped heraldic paintings in churches up and down the country.