There was a George Roberts auctioning his entire house contents and then his house on March 20th 1873. The Barque Windermere arrived from Liverpool in July, so maybe he came back on that, though I have been unable to find a sailing date or destination. The list of the house contents is fascinating, and you also see the vital link the barques provided, and while the papers could advertise what was expected they didn't know with any certainty when the barque would arrive. Once it arrived the adverts changed to 'just arrived' for example ex-Windermere July 1873 :
100 tons Liverpool salt
25 Barrells India Pale Ale (McEwans)
Cases India Pale Ale (ditto)
Cases XXX stout (ditto)
10 Quarter Casks Martells fine brandy
10 Quarter Casks Henessey fine brandy
80 Cases of Hennesey one, two and three star brandy
118 cases of Finest Scotch Whisky
etc etc for the drink, it even included Australian wine
also sewing machines, small steam engine, silk handkerchiefs, blotting paper and stationery, blacksmiths coal, cloth of all descriptions, saddles, spurs, horse blankets, galvanised iron, water filters .. it is incredible to see the details of this British outpost on the other side of the world - I had no idea we even had a footprint there.
The only other mention I have found of George Roberts is that he played a key role in rescuing the Steamer Kilauea, which was the steamer that did the inter-island service. He was presented a gold chronometer watch by the government for "services rendered to the steamer Kilauea on the evening of April 12th, 1871." and at the time he was Chief Engineer of the steamer. Of course there may have been another George Roberts, but as an engineer it wouldn't be a big jump to manage a steamship engine.
Steve