On 25 November 1936, Tolkien delivered “Beowulf: The Monsters and the Critics” to the British Academy, and it was published the next year in the Academy's proceedings. The essay was a redaction of lectures that Tolkien wrote between 1933 and 1936, “Beowulf and the Critics.” (Source.)

These editions are reprints of the Sir Israel Gollancz memorial lecture in 1936, noted in the Proceedings of the British Academy, London, v. 22 (1937).

Here's a review on Medieval Forum written by Tom Sharpe.