Lasting complications of his childhood typhoid fever meant Evans lost his voice in 1880 and had to give up his Preston ministry. He began studying
natural science at
Owens College in Manchester, but by the end of the year he moved to
Oxford. Once home in Oxford, Evans began attending lectures from Welsh scholar
John Rhŷs, who was the first professor of
Celtic at the
University of Oxford. Rhŷs's talks on the
Mabinogion reignited Evans's interest in ancient Welsh manuscripts; he had studied them years before under Alcwyn C. Evans in Carmarthen. Evans had also read the "
Four Ancient Books of Wales" translated by
William Forbes Skene. He was inspired to create his own translation of the
"Red Book of Hergest," one of the four ancient books, as well as a collection of Welsh proverbs. The latter won a prize for poetry and prose at the
National Eisteddfod of Wales in 1884.
Manuscript research Evans then began publishing a series of
facsimiles of major medieval Welsh manuscripts, setting up his own
printing press to create them. After the release of the first volume, "Series of Old Welsh Texts," in 1887, he was awarded an
honorary master's degree by the
University of Oxford. Evans spent the rest of his career transcribing and publishing Welsh texts – often including hand drawn reproductions of the manuscripts' intricate
lettering and imagery. He frequently partnered with Rhŷs until his death in 1915, and the two published several major works in medieval Welsh literature. File:Blackbookofcarmarthen1.jpg|Page 1. File:Blackbookofcarmarthen7.jpg|Page 7. File:Blackbookofcarmarthen9.jpg|Page 9. File:Blackbookofcarmarthen18.jpg|Page 18. File:Blackbookofcarmarthen25.jpg|Page 25. File:Blackbookofcarmarthen39.jpg|Page 39. File:Blackbookofcarmarthen47.jpg|Page 47. File:Blackbookofcarmarthen48.jpg|Page 48. File:Blackbookofcarmarthen81.jpg|Page 81. File:Blackbookofcarmarthen97.jpg|Page 97. File:Blackbookofcarmarthen103.jpg|Page 103. Starting in 1893, Evans was granted a £200 (£21,816 in 2025)
civil-list pension to fund his manuscript research. The series is a "monumental work," covering over 900 manuscripts from the 12th to 19th centuries. He was elected the University of Wales's Court of Governors in the fall of 1897 and served as a "mouthpiece" for Williams during negotiations for a national library. Evans helped Williams secure the
Peniarth Manuscripts — a collection containing some of the oldest and most important Welsh manuscripts in existence, including the
Black Book of Carmarthen,
Book of Taliesin and
White Book of Rhydderch — in 1898, which became the focal point of the new National Library of Wales and one of the driving reasons for its creation. He introduced Williams to the manuscripts' owner,
William Watkin Edward Wynne, and facilitated the collection's sale. When the library formally began construction in 1911, Evans met
King George V and his family —
Queen Mary,
Princess Mary, and the future
King Edward VIII — who travelled to Aberystwyth on July 15 to lay the ceremonial
foundation stone.
Work during retirement In 1905, Evans retired to
Llanbedrog in Caernarfonshire, where he and his wife Edith lived in Tremfan Hall. Then 53 years old, he did not stop publishing early Welsh texts and creating his own prints. Evans's work during his retirement was "nothing short of astonishing, marked by an extremely high level of accuracy produced by hand-typesetting with the utmost care."
Taliesin and rivalry with John Morris-Jones Starting in 1909, Evans's work began to shift toward text interpretation instead of just translation. His theories on the poetry of
Aneirin and
Taliesin — the later especially – were controversial and led to his years-long rivalry with fellow Welsh academic
John Morris-Jones. His most controversial claim was his belief that the
Battle of Catraeth was fought in 1098 A.D. — not the 6th century as is generally accepted. Despite having support from scholars for the factual content of his work, Morris-Jones received little support from the public, who found his response "too acrimonious in spirit" and generally sided with Evans. Evans wrote his own response in Y Cymmrodor; the editors also gave him an entire volume for his work, titled
Taliesin: Or the Critic Criticised, in order to "have now the two sides of the subject laid before them by their respective protagonists." Most of Evans's theories on Taliesin have since been disproved; however, he saw this as academic advancement: ==Death and legacy==