The house at 220 Elgin Street East was built in 1879 by William Garner. At the same time he built the neighbouring houses at 214 and 224 Elgin Street East. All were designed by Silas H. Weekes, best known as the architect of the St. Marys Opera House.

The first occupants of 220 Elgin St. E. were Robert Begg and his family, who rented the house from William Garner. Robert Begg was a store clerk who had been born in Scotland and came to Canada in 1868. The Beggs lived there only briefly. In 1881 William Garner sold the property to Robert J. Armstrong, who moved in with his wife Cornelia. The Armstrongs were retiring to St. Marys from Lakeside, a nearby community in East Nissouri Township.

Robert Armstrong was a native of Northern Ireland and was born on January 12, 1812 in Irvinstown, Fermanagh County.  It is not known when Robert emigrated to North America but it would have been before or during the Great Famine in Ireland which began in 1845.

In 1853 Robert Armstrong, then 41 years old, took title to the west half of Lot 31, Concession 13 in the Township of East Nissouri, north of Lakeside. Probably about this time he married Cornelia Leach. Cornelia was an American, born in Connecticut in 1815. She had a younger sister Caroline, who married Russell Starr. By 1850 Cornelia, still unmarried, was living with the Starrs in Penfield Township, southwest of Cleveland, Ohio.

Whether before or after her marriage to Robert, Cornelia came to Canada and by the time of the 1861 census they were living on the East Nissouri farm. The Armstrongs do not appear to have had children. Robert later gave up farming (although he continued to own the farm until 1881) and became a prosperous merchant. In the mid-late 1860s he began operating a general store in Lakeside and was postmaster in the village from 1868 until his retirement to St. Marys in 1881. The store stood where the United Church now stands at the main corner of the village.

Robert was also appointed a Justice of the Peace, a position he held at the time of the acquisition of the Elgin Street house. Robert and Cornelia were members of the Church of England (Anglican). A few years later, in October 1884, Robert died of a heart attack at age 72. The next year Cornelia moved next door to the corner house at 214 Elgin Street East. Not long after, Cornelia’s sister Caroline Starr and her daughter Augusta came to live with Cornelia. At the time of the 1891 census Caroline had died but Cornelia was still living with her niece Augusta, whom she regarded as her heir.

For many years Cornelia continued to own the house at 220 Elgin Street East, which was rented to a number of tenants.

Cornelia died in February 1900 at age 84 and is buried with her husband Robert and sister Caroline in St. Marys Cemetery.