He studied under William Pether,[1] and began to exhibit at the Royal Academy in 1786, when he showed a portrait and views of Waltham Cross and Canterbury.
[4] The art historian Graham Reynolds sees Dayes' work as "mark[ing] the transition from the eighteenth to the nineteenth century".
[3] Many of his drawings were crowded with figures; among these were two views of the interior of St. Paul's Cathedral on the occasion of the thanksgiving for the king's recovery in 1789, The Trial of Warren Hastings in Westminster Abbey, and Buckingham House, St. James's Park (1780), later hung in the South Kensington Museum.
[1] In 1798 Dayes began to show scriptural subjects, such as The Fall of the Angels (1798), John preaching in the Wilderness (1799), the Triumph of Beauty (1800), and Elisha causing Iron to swim (1801).
He wrote an Excursion through Derbyshire and Yorkshire, Essays on Painting, Instructions for Drawing and Colouring Landscapes, and Professional Sketches of Modern Artists.