His essay on Gray, originally published in the Cornhill Magazine, tells the story of their close friendship, and of their journey to London in 1860 in search of fame.

Buchanan showed more ambition in The Book of Orm: A Prelude to the Epic, a study in mysticism, which appeared in 1870.

He was a frequent contributor to periodicals, and obtained notoriety as a result of an article which, under the pen name of Thomas Maitland, he contributed to The Contemporary Review for October 1871.

[15] Entitled The Fleshly School of Poetry,[16] this article was expanded into a pamphlet (1872),[17] but he subsequently withdrew from the criticisms it contained, and it is chiefly remembered by the replies it evoked from Dante Gabriel Rossetti in a letter to the Athenaeum (16 December 1871), entitled "The Stealthy School of Criticism",[18] and from Algernon Charles Swinburne in Under the Microscope (1872).

Buchanan was also the author of many successful plays, including Lady Clare, produced in 1883, Sophia (1886), an adaptation of Tom Jones; A Man's Shadow (1890), and The Charlatan (1894).

He also wrote, in collaboration with Harriett Jay, the melodrama Alone in London (in which actress Cora Tanner starred).

He is buried in a family grave in the cemetery of St. John the Baptist Church, Southend-on-Sea, Essex, where there is a memorial to him.

Among his poems should also be mentioned: His earlier novels, The Shadow of the Sword, and God and the Man (1881), a striking tale of a family feud, are distinguished by a certain breadth and simplicity of treatment which is not so noticeable in their successors, among which may be mentioned: Meg Blane: A Rhapsody of the Sea, a cantata for mezzo-soprano, chorus, and orchestra by Samuel Coleridge-Taylor, is based on a poem by Buchanan; it was completed in 1902[23] and premiered to great acclaim that October in Sheffield.

[24] Another Buchanan poem "Fra Giacomo" served as the text for a dramatic monologue for baritone and orchestra by Cecil Coles, completed in 1914.