[citation needed] His doctoral thesis at Queen Mary, University of London was "Private performances and amateur theatricals (excluding the academic stage) from 1580 to 1660" (1935).
His portrait, by Thomas William Pattison (1894-1983) hangs in the college hall of St Cuthbert's in Durham.
In 1971 he gave up being general editor of the Revels Plays, a series he had conceived in the mid-1950s in imitation of the New Arden Shakespeare, applying that edition's methods of scholarship to other English plays before 1700.
[4] Following his retirement, friends and colleagues established a prize named the 'Clifford Leech Prize', awarded annually for an outstanding PhD thesis on a dramatic topic completed at the Department of English or the Centre of Drama, Theatre and Performance Studies.
Leech's earliest published works were many essays and articles for scholarly periodicals.