John Evans, recommended him to the General Baptists at Newport, Isle of Wight, then unprovided with a minister; Aspland visited them 17 April 1801, and was requested to remain.
His marriage followed in May; he became secretary to the South Unitarian Society in 1803; he published a sermon, entitled ‘Divine Judgments,’ in 1804; and he left Newport February 1805 to take charge of a larger congregation at Norton, Derbyshire.
The first of these was the Monthly Repository, containing biographical sketches, theological disquisitions, political criticism, &c. This Aspland edited, and he had the opening number ready for February 1806.
In 1812 he was a member of the committee of the Protestant Society for the Protection of Religious Liberty, being one of a deputation, which had an interview with the Prime Minister Spencer Perceval 11 May, only two hours before he was shot.
In 1813 Aspland set up the Hackney Academy at Durham House for training unitarian ministers; he was helping also, by letters and sermons delivered and printed, in the agitation for an act to relieve from penalties persons who impugn the doctrine of the Holy Trinity.
In July 1817 he formed the Non-con Club at his own house, Thomas Noon Talfourd, Southwood Smith, William Johnson Fox, and Walter Wilson being among the members.
On his recovery in 1819, he brought about the formation of the Association for protecting the Civil Rights of Unitarians; and that being the year of the conviction of Richard Carlile for publishing Tom Paine's The Age of Reason, Aspland was engaged in controversy on the subject in the columns of The Times.