He was invested as a knight by King Henry VIII in 1513 and summoned to Parliament as Baron Montagu in the Peerage of England on 12 October 1514.
On 4 November 1538, Montagu along with his wife's uncle, Edward Neville,[3][4] and other relatives, were arrested on a charge of treason by Henry VIII as part of the Exeter Conspiracy, although Thomas Cromwell had previously written that they had "little offended save that he is of their kin".
[citation needed] Montagu's brother Reginald was in exile at the time due to his opposition of Henry's divorce from Catherine of Aragon.
They reported to Thomas Cromwell that although they had "travailed with her" for many hours she would "nothing utter," and they were forced to conclude that either her sons had not included her in their plans for "treason" or she was "the most arrant traitress that ever lived".
It was expected that he would follow his grandmother to the block, but the king did not want to risk unfavorable public opinion and so he was deprived of a tutor and imprisoned in the Tower until his death, possibly from starvation, in 1542 or later.