On 18 November 1795, a nearby fire on Gallowtree Gate reached Phillips' property, destroying all of his books and papers. Following the fire and experiencing some political difficulties in
Leicester (being imprisoned in 1792 for selling
Thomas Paine's
Rights of Man), he returned to London, established premises in Paternoster Row, St. Paul's Churchyard, and founded
The Monthly Magazine in 1796; its editor was
Dr. John Aikin, and among its early contributors were fellow radicals
William Godwin and
Thomas Holcroft. In 1796, Phillips married Elizabeth Griffiths, a milliner's employee and the daughter of Captain John Griffiths of
Tenby. The couple had several children together, including their sons Alfred and Richard, and their daughters, Elizabeth, Laura, and Emily. Phillips built up a prominent fortune based on the speculative commission of newly revised
textbooks and their publication, in a competitive market that had been freed by the
House of Lords' decision in 1777 to strike down the perpetual copyright asserted by a small group of London
booksellers to standard introductory works. His
Juvenile Library published in 1800–03 provided the steady returns of all successful
children's books. By 1807, Phillips was in sufficient standing to serve as a
Sheriff of London, and was
knighted on 30 May 1808 on the occasion of presenting an address to King George III. In 1808, Phillips and his co-Sheriff, Christopher Smith, founded the Sheriff's Fund to provide financial and material assistance to prisoners and their families or dependents. Donations were primarily collected through
poor boxes and allowed prisoners to purchase clothing, food, coal, candles, and other necessities. In the early hours of 29 July 1810, a fire was discovered in
Hanging Sword Alley at the printing office of Mr. Thomas Gillet, which printed and housed some of Phillips stock. Flames destroyed five homes in the surrounding alley, as well as the entirety of Phillips’ valuable stock of books and documents. Popular periodicals such as
The Satirist, or Monthly Meteor and
The Scourge, or, Monthly Expositor of Imposture and Folly discussed the Gillet fire and its connection to Phillips; one of Phillips’ creditors anonymous submitted a letter to
The Scourge detailing his suspicion that Gillet orchestrated the fire to commit
insurance fraud. Another of the contributors to Phillips's
Monthly Magazine was the Scottish novelist
John Galt. Angela Esterhammer has suggested that the character Masano, an irascible Italian printer in Galt's
Andrew of Padua, the Improvisatore (1820), is based on Phillips. ==Retirement and death==