John Ridout McGregor (1829-1900) was the son of Alrick Mortimer McGregor (born 1810) of Prince George’s County, Maryland. John married his first cousin, Mary Eliza McGregor (1831-1916). In the mid-1850s, John R. McGregor was operating a “Paint and Oil Store” in Washington, DC. Here he sold such items as window glass, camphene, spirit gas, sperm,…