Nicholas Leon Brown was the second son of Leon Brown (1862-1922) and his wife Anna Helen Brown (1861-1939). He had one older brother, two younger brothers, and two younger sisters.
He immigrated to the United States in October 1902, at the age of 17, and within a few years had set up a bookshop in Philadelphia at 5th and Pine Street (where around 1904 or 1905 the future publisher E. Haldeman-Julius bought a pamphlet edition of Oscar Wilde's The Ballad of Reading Gaol and mused about how thousands of such booklets could be made available--it was the germ idea of Haldeman-Julius's famous series of booklets that began in 1919 and became known after 1923 as the "Little Blue Books").
Nicholas L. Brown remained primarily a bookseller for the rest of his life. He married Anna Koren (1886-1961), another immigrant from Bialystock, in Brooklyn on 1 June 1910. They would have three children, Constance Ruth Brown (1914-1919), Daniel Coleman Brown (1921-1999), and Ruth N. Brown (1925-2005).
In the early teens, Brown began publishing books, as privately printed limited editions of what passed in those years as classical erotica. By 1916, he was publishing some books under his own name as publisher, first in Philadelphia, and after a move in 1918 in New York. His publishing list was never large, but included volumes of poetry, belles lettres, and translations. Brown published most of the output of Mitchell S. Buck, a Philadelphia heating engineer who translated classical erotica, and wrote modern works on classical themes. His volume Afterglow: Pastels of Greek Egypt 69 B.C. (1924) was published by Brown and includes a preface by Arthur Machen. I have written more fully of Buck and his publications in an entry at Lesser-Known Writers. Brown also published in 1918 a reprint of Sonnets from the Pantagonian (originally 1914) by Philadelphian Donald Evans, and Precipitations (1920), a book of poems by the modernist Evelyn Scott (Scott would marry the British weird fiction writer John Metcalfe in 1930, after five years together as a couple). Other publications include a limited edition of Samuel Putnam's translation of Claude Farrère's Fumée d'opium, as Black Opium (1929), and the occult novel Souls in Hell (dated 1924, but published in December 1923), by John O'Neill, which sports a dust-wrapper blurb by Arthur Conan Doyle.
In February 1931, Brown's bookstore in New York was robbed of rare books and letters valued at $5,000. The letters included ones by George Washington, Benjamin Franklin, Woodrow Wilson, Charles Dickens, and Daniel Webster. Brown's publishing activities seem to have ceased in 1932, and by 1935 he had moved back to Philadelphia where he remained for the rest of his life. Brown died of a sudden cerebral hemorrhage at the age of 61.