His research into the early monastic history of England was assisted by the library built up at Downside by Dom Raymund Webster.
This effort led to a period of major conflict within the community and he was transferred to Ealing Abbey, another teaching establishment, where he lived 1933–1940.
[4] In 1944 Knowles was elected into a research fellowship in medieval studies at Peterhouse in the University of Cambridge, where he would remain for the duration of his academic career.
[7] While pursuing his academic life at Cambridge, Knowles was eventually, at the instigation of Abbot Christopher Butler, exclaustrated from Downside Abbey and finally released from his vows.
[12] He has been criticised for excluding nunneries from consideration in Medieval Religious Houses on the grounds that there was insufficient evidence to draw on (a lack remedied in more recent scholarship).