Very little is known about O’Reilly, and there is only one known example of his work. Painted on glass and backed with card, it does not have the customary fingerpainted base and is rather small for the time. However, it does show use of a needle against washes of black, to create highlights. The piece has a trade label. This dates his work to 1805 and gives his previous occupation as a drawing master.
Source: McKechnie (Author of, British Silhouette Artists and their Work 1760-1860)
O'Reilly (McKechnie Section 3)