Beginning in 1677, Brady held the position of Regius Professor of Physic at Cambridge. He sat as Member of Parliament for the University in 1681 and 1685.[5]
In historical controversy, he was opposed to William Petyt and James Tyrrell, along what would become Tory versus Whig lines, then forming in the Exclusion crisis of the 1680s. Brady is regarded as holding to an uncompromising royalist position.[6] Others on the Whig side were William Atwood, Edward Cooke, and Sir John Somers.
J. P. Kenyon takes him as a pioneer among the royalist scholars of English medieval history, who were working towards a formulation akin to Kenyon's viewpoint.[7]John Pocock[8] regards as "unforgettably damaging" the effect the (proto-)Tory Brady and others made, in attacking the doctrine of the "Ancient Constitution" as a failed description of the real circumstances of political arrangements in the England of the Middle Ages. On the narrow point of the actual legal effects of the Norman Conquest, Brady had been anticipated by Samuel Daniel, in views that are quite close to some modern scholars.[9] He moved from there to argue for absolutism,[10] and that Magna Carta was not a major charter for popular freedom.[11] Brady's ideas drew on Henry Spelman and Robert Filmer.[4]
David C. Douglas remarks that although his motivations as a scholar were at least as political as those of his opponents, his techniques were so far superior that his work remained of importance.[12] Brady was aided in his later work by a position from 1686 in the archives of the Tower of London.[4][13]