- Location Snelling, Barnwell County
- Origin of name Named for Duncan's ancestral home in Scotland
- Other names Melrose
- Current status Privately owned
- 1802 Earliest known date of existence when founded by Joseph Harley
- 1835 House built by Colonel Billy Duncan (Aiken Standard, p. 8B)
The house was spared by Sherman's troops because a woman and sick child were resting in a bedroom upstairs.
- 1911 The house was a boarding house (Aiken Standard, p. 8B).
- 1930s George Herbert Walker, grandfather of President George Herbert Walker Bush (41), purchased the plantation. President Bush used to visit his grandfather at Duncannon as a child (Aiken Standard, p. 8B).
- Early 1940s Walker moved out of the house leaving it to a friend and fully furnished (Aiken Standard, p. 8B).
- ? Walker's friend then gave the plantation to his hunting club (Aiken Standard, p. 8B).
- 1952 Thomas S. "Sandy" and Suzanne Wilson McMillan purchased the house when most of the land was sold to the United States government for construction of the Savannah River Site (Aiken Standard, p. 8B).
- Number of acres 994 in 2011
- Primary crop ?
- Alphabetical list Colonel Billy Duncan; Easterling; Joseph Harley (1802-?); Thomas S. "Sandy" and Suzanne Wilson McMillan (1952-?)); George Herbert Walker (1930s-early 1940s).
- Number of slaves ?
- House is a wooden structure with approximately 4,200 square fee. There is also a guest house on the property.
- 30-15 Plantation File, held by the South Carolina Historical Society
- Philip Lord, President-Elect Has Ties With Area Through Duncannon Plantation, (Aiken, SC: Aiken Standard Newspaper, December 8, 1988)