James Greenwood, the second son in the family of eleven children of James Caer Greenwood and his wife, Mary Ann, née Fish, was born in London in 1831. After leaving school he was apprenticed as a compositor. Later he was employed as an engraver.
On 21st December, 1851, Greenwood married Eliza Hayson (1824–1917), a dressmaker. They had at least three sons and five daughters. His brother, Frederick Greenwood, was a journalist and together they wrote a novel, Under a Cloud (1860). This was followed by several adventure books for boys. He also had several stories published in Beeton's Boy's Own Magazine. One of these stories, King Lion, was later credited as an influence by Rudyard Kipling. His books and stories were often illustrated by the artist, Ernest Griset.
Frederick Greenwood eventually became editor of the Pall Mall Gazette. He employed James to write several articles for the newspaper. His biographer, Alannah Tomkins, points out: "Late in 1865 Frederick commissioned him to spend a night in the casual ward of a London workhouse. He was allegedly reluctant, but agreed to the work when offered a fee of £30 or £40 in advance, and further payment if the resulting articles made a significant impact on the Pall Mall Gazette's circulation. Accompanied by a friend named Bittlestone, a stockbroker, he entered Lambeth workhouse for a night in January 1866, both men having adopted clothing appropriate to occupants of the casual ward, which housed vagrants seeking overnight shelter. They remained in the workhouse for fourteen hours and emerged the following morning to be collected by Frederick's carriage."
Greenwood wrote: "No language with which I am acquainted is capable of conveying an adequate conception of the spectacle I then encountered. Imagine a space of about 30ft. by 30ft. enclosed on three sides by a dingy whitewashed wall, and roofed with naked tiles which were furred with the damp and filth that reeked within. As for the fourth side of the shed, it was boarded in for (say) a third of its breadth; the remaining space being hung with flimsy canvas, in which was a gap 2ft. wide at top, widening to at least 4ft. at bottom. This far too airy shed was paved with stone, the flags so thickly encrusted with filth that I mistook it first for a floor of natural earth."
He added: "Those beds were placed close together, every occupant being provided with a rug like that which I was fain to hug across my shoulders. In not a few cases two gentlemen had clubbed beds and rugs and slept together. In one case, to be further mentioned presently, four gentlemen had so clubbed together. Many of my fellow-casuals were awake - others asleep or pretending to sleep; and shocking as were the waking ones to look upon, they were quite pleasant when compared with the sleepers. For this reason the practised and well-seasoned casual seems to have a peculiar way of putting himself to bed. He rolls himself in his rug, tucking himself in, head and feet, so that he is completely enveloped; and, lying quite still on his pallet, he looks precisely like a corpse covered because of its hideousness. Some were stretched out at full length; some lay nose and knees together; some with an arm or a leg showing crooked through the coverlet. It was like the result of a railway accident; these ghastly figures were awaiting the coroner. From the moral point of view, however, the wakeful ones were more dreadful still. Towzled, dirty, villainous, they squatted up in their beds, and smoked foul pipes, and sang snatches of horrible songs, and bandied jokes so obscene as to be absolutely appalling. Eight or ten were so enjoying themselves - the majority with the check shirt on and the frowsy rug pulled about their legs; but two or three wore no shirts at all, squatting naked to the waist, their bodies fully exposed in the light of the single flaring jet of gas fixed high upon the wall."
The articles about the workhouse appeared in three successive issues of the Pall Mall Gazette. According to Alannah Tomkins "Greenwood's revelations of squalor, neglect, and degradation, and maladministration by the workhouse authorities, together with the shock of his and his companion's personal experiences (submerged in the filthy bathwater and sharing a bed with paupers), caused a sensation." The articles were reprinted in full in The Times, and they were issued later in the year as a pamphlet. It has been argued that Greenwood was the first journalist to use the pioneering technique of temporarily adopting the dress and circumstances of others and therefore provided a model for successors like Jack London, Mary Higgs and George Orwell.
Sympathetic to the plight of the working-class, Greenwood wrote several articles highlighting the problems of poor housing and public heath for the newspaper. His investigations into poverty also appeared in the books, Unsentimental Journeys, or, Byways of Modern Babylon (1867) and Seven Curses of London (1869). Greenwood developed ideas that resulted in him attempting to distinguish between the deserving and undeserving poor. He also proposed emigration to the colonies as a remedy for pauperism. During this period Greenwood was described as "a short, squarish, good-humoured man, dressed in a long black frock-coat, and black tie - the cut of a slum missionary".
In 1871 Greenwood was commissioned by Michael Bass, to investigate working conditions in the railway industry. The articles appeared in the Daily Telegraph and exposed the conditions endured by railway workers. As a result Bass helped finance the formation of the Associated Society of Railway Servants Union. He also provided generous support for the Railways Servants' Orphanage at Derby. For a while, Greenwood became the editor of a new journal, the Railway Service Gazette.
Greenwood created great controversy in 1874 by writing an article for the Daily Telegraph about attending a fight in Hanley, Staffordshire, which a man fought a dog. The account aroused public anger and the Royal Society for the Prevention of Cruelty to Animals attempted to trace the organizers of the fight. However, Greenwood was unable to provide further details to back-up his story.
In 1883 he published Odd People in Odd Places. He stated in the preface that the book contained pen portraits of the "homes, haunts, and habits of some of the lower grade of the great community" of London. Greenwood later became involved in philanthropy and established two funds for children, to provide outings to the countryside and to supply Christmas hampers. Greenwood also published a books about his experiences as an observer in the London police courts. His final book, published in 1905, included interviews with the inmates of lunatic asylums.
James Greenwood found it difficult to find work in the last 30 years of his life and endured the kind of poverty he described in his earlier writings. He died at the home of his daughter in Catford on 11th August 1927, at the age of ninety-six.