Born in Chancery Lane London, the son of William Baker, a clerk in Chancery. Apprenticed at the age of 15 to John Parker a bookseller. At the close of his indentures in 1720 he became involved with the education of deaf-mutes, and ‘his services being in great demand among the upper classes, he soon realised a substantial fortune'. His remarkable success attracted the attention of Daniel Defoe whose daughter Sophia Baker he subsequently married in April 1729.
Until the late 1730s Baker wrote and published poetry, and in 1728, under the name Henry Stonecastle he began, with Defoe, the Universal Spectator and Weekly Journal. He is said to have been responsible for the introduction of rhubarb into England.
Baker had a wide-ranging interest in natural history which resulted in his becoming involved in microscopy, a subject on which he published books in 1743 and 1753, both of which went through several editions, and in beetles which he appears to have collected. He published a note on 'Some curious experiments and observations on a beetle that lived three years without food' in Phil.Trans.R.Soc., 41, 1740, 441-448.
Chalmers-Hunt (1976) records that Baker’s antiquarian and natural history collections were sold at auction 13-23 March 1775, shortly before his death in the same year.
Baker was elected FSA and FRS in 1740, and was involved with the establishment of the Society of Arts in 1754. He is listed in DNB. which records other sources. (MD 9/01)