|British photographers had, since the turn of the century, printed portraits on post cards.
To qualify for postcard rate of postage, the cards have the words POST CARD printed on the back.
Sometimes the French "Carte Postale" will be added underneath.
A foreign heading or more commonly a plain back with a four line address panel, is a sign that the photograph is probably of Continental origin.
Deckelled edges were also a favourite of continental photographers. A few British photographers produced deckel edges but it was standard practice on the Continent.
It is highly possible the photograph is foreign or was taken on the Continent.