He was afterwards educated for the independent ministry, under Philip Doddridge, at Northampton, where he first took up his quarters in 1739; and settled at Daventry in 1746, originally as assistant to James Floyd.
Under Ashworth, Daventry Academy became a leading seat of culture among liberal independents and presbyterians, who at that time were close, and shared views on theology and church polity.
The academy covered languages, biblical criticism, and ecclesiastical history quite weakly; its staple was dogmatics and philosophy, including psychology (then called pneumatology), ethics, and physics.
His most distinguished scholar was Joseph Priestley, who says that Ashworth took "the orthodox side of every question" in theology and philosophy, the sub-tutor, Samuel Clark, "that of heresy".
Doddridge's plan of referring to authors on all sides of every question, and requiring his students to give an account of them, was pursued by his successors.