By 1896 Wintle was writing for the Windsor Magazine.[2] He then joined the Harmsworth staff, working for Lord Northcliffe. There he worked on magazines, and the Harmsworth Encyclopaedia, a part-published (=serialized) work. Later he was director of a publishing house.[1][3]
As naturalist, Wintle was known as a shell collector; his collection went to that of Arthur Blok.[4] He became a fellow of the Zoological Society during 1899. He joined the Malacological Society of London also, during 1916, and was its Secretary during 1919;[1] he was elected to the Conchological Society of Great Britain and Ireland during 1917.[5]
Interested in Christian religion, Wintle donated to the Anglican church in Chiswick. He spent time on Caldey Island with the Benedictines there.[1] A British Museum list of those presenting zoology specimens during 1920 includes a Brother W. J. Wintle.[6] He later became a Roman Catholic convert.[1]
One of Wintle's pieces of journalism, Life in Our New Century from 1901, was published originally in the Harmsworth Magazine.[7]
Wintle also composed and published various books:
Armenia and its Sorrows (1896),[8] prompted by the Hamidian massacres. A letter of endorsement from W. E. Gladstone to Wintle was used to publicise the book.[9]
Ghost Gleams. Tales of the Uncanny (1921).[14] These are regarded as ghost stories for children, and A Light in the Dormitory has been included in an anthology.[15]
Wintle wrote for the Sunday School Union, using the pseudonym "John Upton" for a weekly article for the Union's Sunday School Chronicle. With them he published:[1]
The Story of Florence Nightingale (1896)
The Story of Albert the Good (Prince Consort) (1897)[16]
Dr. J. L. Phillips ... A Biographical Sketch (1898)[17] with Mary Phillips; biography of James Liddell Phillips (1840–1895)[18]
The Story of Victoria, R.I.: Wife, Mother, Queen (1901)[19]
Florence Nightingale and Frances E. Willard: the Story of Their Lives, with Florence Witts, undated[20]