The eldest son of Charles Winn of
Nostell Priory, near
Wakefield, he lived in the 1850s in another family property, Appleby Hall near
Scunthorpe, and married Harriet Dumaresque. Aware that the area had produced iron in Roman times, he searched for ironstone on his land, and found it in 1859. He marketed it to iron-makers, leased land for mining, mined his own ore and encouraged the building of iron works. To transport the iron and to bring the coal necessary for the smelting, Winn campaigned for a railway to be built, which required the passage of an
Act of Parliament. The
Trent, Ancholme and Grimsby Railway opened in 1866, and Winn also built 193 houses in New Frodingham and enlarged the local school. Later, he financed the building of Scunthorpe Church of England School and St John's Church. He was
Member of Parliament (MP) for
North Lincolnshire from 1868 to 1885, and served as a
junior Lord of the Treasury (
Government whip) in
Disraeli's
second government, from 1874 to 1880. He was Conservative Party Chief Whip from 1880 to 1885. Here he had to deal with
Lord Randolph Churchill and the
Fourth Party. He was later ennobled as
Baron Saint Oswald, of
Nostell in the
West Riding of the
County of York in 1885, when the Conservatives were returned to power. He returned to live at Nostell Priory when he inherited the house from his father in 1874, but his mother and unmarried sisters continued to live at
Appleby. His son
Rowland (1857–1919) was MP for
Pontefract from 1885 to 1893. His daughter Maud married Lt-General Alan Montagu-Stuart-Wortley. In 1897, Baron and Lady St. Oswald and their daughter Maud were guests at the Duchess of Devonshire's Diamond Jubilee Costume Ball. His daughter Laura married
Valentine Lawless, 4th Baron Cloncurry, an Irish nobleman. ==Arms==