French Antique Warehouse has dated this piece to the 19th Century.
The projecting backing can either be trimmed away if desired, or used as a fixing and decorated.

Dating to the nineteenth century, it is made from mirror glass and gilt wood, and originates from France.
In good age related condition, it has a small amount of silvering loss towards the top and some minor imperfections in the glass, and some rubbing to the gilt, all of which gives it the character of age and use without inhibiting function.
French Antique Warehouse has dated this piece to the 19th Century.
You can view the stock and full dealer information on the French Antique Warehouse Profile Page