Long article by Borrow published in Quarterly Review, January 1861.
According to Knapp Borrow wrote the article from which The Welsh and Their Literature was made in 1830. In 1860, with Borrow planning to publish his translation of Ellis Wyn’s Sleeping Bard, Borrow revamped the 1830 article and sent it to John Murray for publication in Murray’s Quarterly Review. The piece was accepted but published without Borrow’s name.
The article gives a history of the Welsh, their literature and “reviewed” Borrow’s recently published translation of Ellis Wynn’s Sleeping Bard. Knapp says:
It is in fact Borrow’s own (and the only) review of The Sleeping Bard, which, however, is well written, and had the decisive result of selling off the whole edition in a month [src: Life of George Borrow, Volume 2, p. 196]
Later, Herbert Wright made the link between The Welsh and Their Literature and Borrow’s unpublished work Celtic Bards, Chiefs and Kings, and was able to see the far from being an article, The Welsh and Their Literature was in fact the first half of the latter book.
source: Life of George Borrow, Knapp