John Campbell was still resident on Macleay Island and was supervising the sugar plantation there in early July 1869, when he gave evidence before the Select Committee on the Operation of "The Polynesian Laborers Act of 1868". The Campbells employed South Sea Islander labour, and Campbell had recently returned 44 Islanders from Macleay Island to their homes. His son Frederick had brought them in the "Black Dog" from Erromanga, Sandwich (now Efate) & Tanna Islands (all of which are now part of Vanuatu) about April 1866, and their 3-year contract was over. By October 1869, John Campbell had nearly completed the erection of a sugar mill on Macleay Island, but whether construction of the mill was financed by J & G Harris or the Campbells is not clear. By the end of 1869 he had under sugar and a mill. The same amount of land was under sugar in 1870. In 1885, an unnamed author (possibly RS Hurd, Harris' manager on Macleay Island in the early 1870s) described the improvements on the southern half of the island during John Campbell's time there:  ""Here was the residence of the late Mr John Campbell, and some thirty acres were under cultivation for sugar-cane, as well as peach trees, bananas, and other fruits. There was in those days a good cypress pine house erected there, a large and well-stocked fruit and flower garden, well laid out and a complete plant for sugar-boiling and salt- making. All this, however, is a thing of the past . . . this ridge where the house was built is admirably suited for well-sinking, as the ground retains the water as well as if it were puddled. Mr Campbell had a well sunk there some 8ft deep, and it lasted out the driest season with no perceptible leakage . . . this is where the view is par excellence of the whole place to be obtained. Standing on the top of the hill, the ground slopes away in front to Pininpinin Point . . . In front are Karragarra and Russell Islands . . . this deep channel separating Macleay and Karragarra is one of the deepest parts of the bay, and well stocked with fish, Mr Campbell constructed a fish trap at the end of the jetty, and told the writer that he had caught large rock cod in it and abundance of mullet. There is a very pretty walk through the old plantation towards Perrebinpa Point, which is a narrow gravelly neck of land, reaching a long way out.