Campbell-Mackie Artwork / Print

Bought this recently not knowing much about it. Clearly signed and dated. Campbell-Mackie 1921. Seems to be printed on fabric and the central panel is recessed.

There is a lot of info online about the artist / architect online, but the mystery is why I cant find anything out about this piece. There seems to be nothing else similar anywhere and hoping someone here can shed some light on rarity, what is etc etc.

Nice original frame evidenced by the original Glasgow framers label who was in business at the same date as the picture