His father, Charles, was auditor-general of the Duchy of Cornwall, while Frederick was Prince of Wales; was MP for Westminster in 1722, for St. Germans in 1734, for Camelford in 1741, and for Northampton in 1754, and died on 29 May 1759.
[citation needed] Frederick's mother, Ann Colladon, well known in society after her husband's death, was an intimate friend of Mary, dowager-countess of Gower (the widow of John Leveson-Gower, 1st Earl Gower), and of Mary Delany, in whose published 'Correspondence' she frequently figures as 'my Mrs Montague', in order to distinguish her from the better known Elizabeth Montagu.
He seems to have won Paris's college declamation prize, and his oration was published at the request of the master and fellows as 'Oratio in laudes Baconi,' Cambridge, 1755, 4to.
[1] At Cambridge, Montagu made the acquaintance of the poets Thomas Gray and William Mason, which he sedulously cultivated afterwards.
In 1780, he was generally expected to succeed Fletcher Norton, 1st Baron Grantley as speaker of the House of Commons.
He became a Lord of the Treasury in 1782 under Charles Watson-Wentworth, 2nd Marquess of Rockingham, and again in 1783 in William Cavendish-Bentinck, 3rd Duke of Portland's coalition ministry.