He passed his examination as a surgeon on 19 February 1755, and settled in Bristol in practice of his profession.

[1] His History and Antiquities of Bristol was announced early: an engraving of him, by William Walker, from a portrait by Jan van Rymsdyk, ‘ætatis 31’ (i.e. in 1764), was issued 25 years before the book itself was printed.

"’ In his research, though acquaintances of his such as Catcott and Burgum, the pewterers, he met Thomas Chatterton the forger.

[2] Many of Chatterton's fabrications did make their way into his History (1789) when it finally came out long after the forger had died, damaging Barrett's reputation severely.

After Barrett's death the antiquarian forgeries of Chatterton passed to the British Museum, via Robert Glynn.