The papers of Robert Lemon consist of three separate documents (one of which spans 4 pages) of notes on a portrait of Milton owned by Lemon, detailing its authenticity and also the need to establish a National Gallery of Portraits. One of these documents is dated 16 March 1853. The notes are thought to have been written by Lemon in preparation for a talk he gave on the Milton portrait when he exhibited it to the Society of Antiquaries.
Also includes draft of a letter by Lemon to the editor of The Athenaeum magazine dated 4 December 1855 concerning the establishment of a National Gallery of Portraits. This letter references the talk Lemon gave to the Society of Antiquaries in March 1853.