Tillyard was born in Cambridge, where his father had served as mayor. He was educated at the Perse School and Jesus College. He was interested in the classics and archaeology, and in 1911 went to Athens to study at the British School of Archaeology. His knowledge of Greek helped him during the First World War, where he served with the British Expeditionary Force, the Salonika Force and then as liaison officer with the Greek headquarters. He was made an Officer of the Order of the British Empire in the 1919 Birthday Honours "for services rendered in connection with military operations in the Balkans." He also received the War Cross from Greece. Following the war, he returned to Cambridge and devoted himself to the newly established English School. According to The Times, "Although not one of the Founding Fathers of the School, he rapidly became one of its central figures and its leading statesman — a position which, in spite of many changes in organization and personnel, he never really lost until his retirement from his University Lectureship in 1954. His influence was not mainly due to his very considerable gifts as a University politician; it was essentially the result of his whole-hearted devotion to the cause of English. Others may have won more widespread celebrity as scholars or as critics, but everyone in Cambridge knew that Tillyard, because of his selfless and unremitting thought and care for the good of the School, was its chief mainstay." Tillyard was a Fellow in English at Jesus College, later becoming Master. He is known mainly for his book The Elizabethan World Picture, as background to Elizabethan literature, particularly Shakespeare, and for his works on John Milton. He is credited with having put forward the view that Elizabethan literature is not representative of "a brief period of humanism between two outbreaks of Protestantism", but rather representative of a theological bond in England that allowed for a continuation of the medieval view of World Order. His historical scholarship and contextual analysis informed the study of 16th-century literature and became the foundation for much of what Cambridge undergraduates would study in preparation for their examinations.
The Hope Vases: a Catalogue and a Discussion of the Hope Collection of Greek Vases with an Introduction on the History of the Collection and on Late Attic and South Italian vases
Lamb's Criticism. A Selection from the Literary Criticism of Charles Lamb
Milton: Private Correspondence and Academic Exercises with Phyllis B. Tillyard
The Poetry of Sir Thomas Wyatt: A Selection and a Study
Shakespeare's Last Plays
The Personal Heresy: A Controversy with C. S. Lewis
The Elizabethan World Picture: A Study of the Idea of Order in the age of Shakespeare, Donne & Milton
Published by Pelican Book: The Elizabethan World Picture, 1972 and later prints.