This operation may never have been run by a Ewing but it is unsurprising that it has Ewing over the door as it was Ralph Ewing who initial identified the deposits of Phosphate.
From the Proceedings of the Royal Society of New Zealand 1868-1961 http://rsnz.natlib.govt.nz/volume/rsnz_38/rsnz_38_00_005530.html
Discovery of the Phosphate.—Meanwhile, Mr. Ralph Ewing, of Whare Flat, Dunedin, had been travelling in America, and had inspected the phosphate-deposits of Florida. Returning to New Zealand, he speedily realised the true nature of the “decomposed limestone,” and in June, 1902, he announced his discovery. Then the lime-burner and the farmer understood why the poor limestone made just as good a land-manure as the ordinary limestone.
Mr William Ewing was a prominent business man and is the Ewing out of Brown and Ewing that we encountered in the Wains Hotel entry. I believe Ralph is his son residing on the family farm at Whare Flat.
As an aside William came to Dunedin on the ship Sevilla in 1859 and a listing of passengers shows a Mary Forsyth listed directly below him (refer)
http://freepages.genealogy.rootsweb.ancestry.com/~nzbound/sevilla1859.htm
She was to become his wife which shows that he put his time on board ship to good use.
The business itself was in operation from 1902 to 1924 and then a brief restart in 1943 to 1944 when I suspect WWII interupted supplies from overseas.
It seems that this business may yet return to life (albeit not Ewing itself but the deposit) as the cost of imported phosphate has rocketed in recent years making this deposit once again economic to mine.
