He was educated at Christ's College, Cambridge,[3] was admitted to Middle Temple on 6 November 1585 and was Called to the Bar on 9 June 1592.

He was elected recorder of London in 1603, and in 1616 was made Chief Justice of the King's Bench, in which office it fell to him to pass sentence on Sir Walter Raleigh in October 1618.

[2] In 1620, he was appointed Lord High Treasurer, being raised to the peerage as Viscount Mandeville and Baron Montagu of Kimbolton, Huntingdonshire.

[2] Although from the beginning of his public life in 1601, when he first entered Parliament, Manchester had inclined to the popular side in politics, he managed to retain to the end the favour of the King.

[4] Another son he had with Catherine Spencer was James Montagu who served as MP for Huntingdon in the English House of Commons alongside Oliver Cromwell in 1628.