On 4 November 1538, Montagu along with his wife's uncle,
Edward Neville, 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". Montagu's brother
Reginald was in exile at the time due to his opposition of Henry's divorce from
Catherine of Aragon. They were committed to the
Tower of London and Lord Montagu was attainted and his honours forfeited on 2 December 1538. Neville was beheaded on 8 December 1538, and another cousin,
Henry Courtenay, 1st Marquess of Exeter, was executed on 9 December 1538. On 9 January 1539, all of the remaining arrestees were beheaded, with the exception of Henry's brother
Geoffrey Pole. Ten days after Montagu's arrest, his mother was arrested and questioned by
William Fitzwilliam, and
Thomas Goodrich, Bishop of Ely. 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". On 27 May 1541, the 67-year-old Lady Salisbury was beheaded in the Tower of London. Lord Montagu's son Henry was committed to the Tower at the same time as his father. It was expected that he would follow his grandmother to the block, but the king did not want to risk unfavourable 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. ==Marriage and issue==