Bennett had early shown a taste for historical inquiry, and had copied the parish registers of his district. In 1899, he began writing in the Traethodydd. In 1905 he visited Trevecka to examine the manuscripts there, and thenceforth he spent his winters at Trevecka, returning to his farm with each spring. It was he who made the copies of the Trevecka letters for printing in the supplements of the C.M. Historical Journal; to the same journal he contributed numerous articles. He published the following books: Blynyddoedd Cyntaf Methodistiaeth (Caernarvon, 1909), Methodistiaeth Trefaldwyn Uchaf (Bala, 1929), Methodistiaeth Trefeglwys (Llanidloes, 1933), Methodistiaeth Cemaes (Llanidloes, 1934), Methodistiaeth Caersws (Llanidloes, 1938). After his death, some of his addresses were published, with a short memoir, in Cyfrol Goffa Richard Bennett (Bala, 1940).

Bennett was a researcher and historian of unusual distinction, especially when his total lack of training is remembered. Not only was his detailed knowledge of the Trevecka MSS. well-nigh miraculous, but he had a very wide perspective of Methodist history. No one was more deserving than he of the honorary degree of M.A. conferred upon him by the University of Wales in 1932.