Mackelvie established a perpetual memorial for himself in Auckland, New Zealand, by his endowment of that city with a valuable art collection selected by himself in Europe, and a rich bequest for the maintenance of a permanent gallery. To further this purpose the Municipal Corporation, in September 1891, resolved to erect a Mackelvie annexe to the handsome building, in which the Grey Literary Collection and the Auckland Free Public Library are placed.
Mackelvie in early life was engaged as supercargo of a vessel during the Crimean War, and subsequently as purser on an Atlantic liner. Leaving the sea, he obtained an appointment in a large mercantile house in London, and was so engaged in 1865, when Dr. Campbell, desiring a partner to take charge of his business while he visited Europe, entered into an agreement with Mackelvie, who came to Auckland and assumed the direction of the business of Messrs. Brown, Campbell & Co. until 1870, when the partnership terminated by effluxion of time. During that short period, however, Mackelvie had amassed a fortune by means of judicious mining investments on the Thames goldfields. He returned to Europe a month or two after quitting his connection with Brown, Campbell & Co., and lived in retirement, employing a large part of his time in collecting the art treasures which he had resolved to bequeath to the city where his fortune was made. Many valuable paintings and sketches were forwarded to Auckland during his lifetime, and at his death, which took place on 4 June 1885, by the terms of his will, after providing for about £35,000 legacies, in some of which the trustees have a reversionary interest, the balance of the estate was left in trust for the people of Auckland. The legacy, owing to the great depreciation in all kinds of property, is very much less than the testator no doubt intended, but, including the reversionary interest in legacies, the trustees hope the amount may not be far short of £30,000, besides the valuable collection now in the Art Gallery. During his stay in the colony Mackelvie was director of the Bank of New Zealand, the New Zealand Loan and Mercantile Agency Company, and other companies.