"Edited with an introduction by W. S. Lewis."
British Library GB64-18882 (old format)
US publication date (inferred) and price from listing NY Times 1964-11-05 p42 "Books Today"; under heading "Fiction", only four, the Oxford English Novels volumes (below).
Price from publisher advertisement "New, from Oxford" NY Times 1964-11-29 pBR22, under subheading "A New Series: The Oxford English Novels":
"offers the classic novels of our literature beginning with the 18th century, in definitive texts. [...]
The first four --";
this one second-listed, $3.50.
(See the Pub. Series record for entire description.)
This publication not found 2018-04-26 in automated search ('castle of otranto') of 1964 UK newspapers, nor The Irish Times.
Cover image from Amazon 2018-04-27, should be checked.