In 1907 he was awarded a Heriot Fellowship at Edinburgh and appointed lecturer in English literature at the University of Dijon.
In 1938 he held the Sandars Readership in Bibliography at Cambridge University lecturing on "The judicious marriage of Mr Hooker and the birth of ‘the Laws of Ecclesiastical Polity’."
He then served as senior fellow and assistant director of the Shakespeare Institute at the University of Birmingham.
[1] In Who's Who Sisson listed amongst his recreations the "Record Office and detective stories",[2] and his works on Thomas Lodge and Other Elizabethans (1933) and the Lost Plays of Shakespeare's Age (1936) were the fruits of his detailed knowledge of archival sources.
His 1960 work Shakespeare's Tragic Justice analysed Macbeth, Othello, Hamlet and King Lear.