Ritson devoted his spare time to literature, and in 1782, he published an attack on Thomas Warton's History of English Poetry.

The tone of his Observations, in which Warton was treated as a pretender, charged with cheating and lying to cover his ignorance, caused a sensation in literary circles.

Bishop Percy was next subjected to a furious onslaught in the preface to a collection of Ancient Songs (printed 1787, dated 1790, published 1792).

In a letter (14 March 1803) to Samuel Taylor Coleridge, Robert Southey wrote that "Ritson is the oddest, but most honest of all our antiquarians, and he abuses Percy and Pinkerton with less mercy than justice".

As early as 1796, Ritson showed signs of mental collapse, and on 10 September 1803, he became completely insane, barricaded himself in his chambers at Gray's Inn, made a bonfire of manuscripts, and was finally forcibly removed to Hoxton, where he died.

[17] Biographer Bertrand Harris Bronson has noted that based on excerpts from Ritson's daily journal his vegetarian diet consisted of muffins, cake, cheese, bread, butter, milk, beer and ale.