O'Neill was born in Bloomsbury, London on 20 April 1784, the son of Jeremiah O'Neill, an architect. He exhibited at the Royal Academy during 1800–04.[1][4] He was a drawing master at Oxford and Edinburgh, then moved to Bath in 1813.[5]
In 1821 he settled in Bristol and worked almost exclusively thereafter for George Weare Braikenridge. Most of the commissioned works were in monochrome wash.[1][4] Some of his surviving drawings suggest that he also undertook commissions for architectural alterations. He does not seem to have participated in the activities of the Bristol School of artists.[5]
^ abcMatthew, H.C.G.; Harrison, Brian (2004). Oxford Dictionary of National Biography, Vol. 41. New York: Oxford University Press. p. 846. ISBN0-19-861391-1.
^ abGreenacre, Francis (1973). The Bristol School of Artists: Francis Danby and Painting in Bristol 1810–1840 (exhibition catalogue). Bristol: City Art Gallery, Bristol. p. 255.
^Stoddard, Sheena (2001). Bristol before the Camera: The City in 1820–30. Bristol: Redcliffe. p. 5. ISBN1-900178-68-0.