​Gilbert Penrose James (Gilbert P. James, or simply Gilbert James) was born in 1865 in Everton, Liverpool. He was the son of Richard Frederick James (1822-1903) from Falmouth, Cornwall, and Harriet Agnes Hiles (1844-1937) from West Derby. His father was a stationer’s cashier and his mother a school teacher. They married in 1865 after Gilbert's birth. He had an older brother Penrose and seven younger sisters. Six of them had the same middle name as Gilbert - Penrose.
We hardly know anything more about the family except they lived in West Derby in 1881. We also know that Gilbert lived alone in 1891, in Soho, London, and at least from 1901, at St. Pancreas, London, where he stayed registered until his death. He was admitted to Horton Mental Hospital in 1937 and transferred to Long Grove Mental Hospital in 1939, where he died in 1941 from the consequences of paralytic dementia. It's hard to tell how long he suffered from mental illness, very likely caused by syphilis, which possibly started years before because he didn't create anything after 1926.
How did Gilbert James become an artist? We know his first job was in the office of the merchant who traded corn. He befriended an artist Sidney Herbert Sime (1865-1941) with whom he later collaborated on some projects, but we don't know how much of the influence their friendship had on Gilbert's decision to leave the predictable office job for the adventure of becoming an artist. Anyway, we know from the census from 1891 he declared himself a student of painting. Gilbert had his first exhibition, when he was still in Liverpool, at the Walker Art Gallery in 1889 and 1890. Shortly after, he moved to London where he worked for numerous newspapers and magazines: Black and White, Pick–me–up, The Butterfly, The English Illustrated Magazine, The Idler, The Ludgate Monthly, The Pall Mall Magazine, The Quartier Latin, The Sketch, The Sphere, The Tatler, and others.
His work was of varying quality which is seen from the letters of readers sent to the publishers. Some praised his works and others described the same works as abomination. Some of his illustrations were used for books, which eventually led to his first commissions for literary works. The most important work by Gilbert P. James was undoubtedly a series of illustrations of Rubaiyat of Omar Khayyam published in different magazines and eventually in book editions. The book editions were reprinted several times in different formats and can be considered quite a commercial success. Gilbert James capitalized on it by a large number of commissions during the time of reprints (approximately till the beginning of the First World War).

We can also add he wrote at least one book: Toby Tan and His Little Dog: or, The Great Detective of Fairy Land, but the book was illustrated by Charles Pears (1873–1958). The book was published by Hodder & Stoughton, London in 1903.
His style didn't fit any particular artistic movement. He was a pretty good line illustrator, but most of the critics agree he had problems with perspective and the usage of colors. While he managed to catch the atmosphere of Orientalism with black and white drawings, his color palette was completely off (compare his work with Edmund Dulac).

This is a list of books illustrated by Gilbert James (some of the years of publishing are just estimates):
  • The Making of a Saint: a Romance of Medieval Italy by W. Somerset Maugham, L. C. Page and Co., Boston, 1898
  • The Rubaiyat of Omar Khayyam, George Routledge & Sons Ltd., London, and E. P. Dutton & Co., New York, 1904
  • Sunshine and Sentiment in Portugal by Gilbert Watson, Edward Arnold & Co., London, 1904
  • Enoch Arden and The May Queen by Lord Alfred Tennyson, Astolat Press, London, 1905
  • Aucassin and Nicolete, George Routledge & Sons Ltd., London, and E. P. Dutton & Co., New York, 1905
  • Poems by Matthew Arnold, George Routledge & Sons Ltd., London, and E. P. Dutton & Co., New York, 1905
  • The Books of Ruth and Esther, George Routledge & Sons Ltd., London, and E. P. Dutton & Co., New York, 1905
  • Christmas Carols by T. C. & E. C. Jack, London & Edinburgh, 1906
  • The Land of Play by Mrs Graham (Ada) Wallas, Edward Arnold & Co., London, 1906
  • Faust: a Drama by Goethe, George Routledge & Sons Ltd., London, and E. P. Dutton & Co., New York, 1906
  • Cupid and Psyche, George Routledge & Sons Ltd., London, and E. P. Dutton & Co., New York, 1906
  • Patient Griselda (Clerk's Tale) by Geoffrey Chaucer, George Routledge & Sons Ltd., London, E. P. Dutton & Co., New York, 1906
  • The Song of Songs, George Routledge & Sons Ltd., London, and E. P. Dutton & Co., New York, 1906
  • A Selection from Grimm’s Fairy Tales, Siegle, Hill & Co., London, 1906
  • A Selection from Hans Anderson’s Fairy Tales, Siegle, Hill & Co., London, 1906
  • A Selection from the Arabian Nights, Siegle, Hill & Co., London, 1907
  • The Queen Bee and Other Nature Stories by Carl Ewald, Thomas Nelson & Sons, London, 1907
  • The Ugly Duckling and Other Stories by Hans Christian Andersen, Thomas Nelson & Sons, London, 1909
  • Poems of Tennyson by Lord Alfred Tennyson, Caxton Publishing, London, 1910
  • Mind your own Buzziness, Siegle, Hill & Co., London, 1912
  • Tristan and Iseult:  an Ancient Tale of Love and Fate, Thomas Nelson & Sons, London, 1912
  • The Myths of Mexico and Peru by Lewis Spence, George G. Harrap & Co., London, 1913
  • William the Silent by Agnes M. Miall, George G. Harrap & Co., London, 1914
  • The Princess Athura: a Romance of Iran by Samuel W. Odell, George G. Harrap & Co., London, 1914
  • Hero Tales and Legends of the Serbians by W. M. Petrovitch, George G. Harrap & Co., London, 1914
  • The Story of Alfred the Great by Annie E. Mackilliam, George G. Harrap & Co., London, 1914
  • The Story of the Buddha by Edith Holland, George G. Harrap & Co., London, 1916
  • Hans Andersen’s Tales by Kathleen FitzGerald, George W. Jacobs, Philadelphia, 1919
  • Tales of Serbian Life by E. C. Davies, George G. Harrap & Co., London, 1919
  • The Five Jars by M. R. James, Edward Arnold & Co., London, 1922
  • The Silver Trumpet by Owen Barfield, Faber & Gwyer Ltd., London, 1925
  • ​Trine, In Tune with the Infinite by Ralph Waldo Leopold B. Hill, London, 1926

That's about all. Or, is it?