He was subsequently a pupil in the school of James Mathews Leigh in Newman Street London, and practised first as a portrait artist painting Charles Greville, Lord Ebury and others.

His pictures suited the taste and appealed to the religious sentiment of a large portion of the public, and their popularity was increased by a wide circulation of engravings.

He consequently determined to exhibit his next pictures in a separate gallery of his own in Bond Street, London and there in 1883, and the following years, his Anno Domini and Zeuxis at Crotona met with great commercial success.

Long died from pneumonia resulting from influenza, at his home, "Kelston" in Netherhall Gardens, Hampstead, on 15 May 1891, in his sixty-second year.

Long had considerable practice as a portrait painter but his success in that line was not conspicuous, although he obtained high patronage and very large prices.