According to the 1684 visitation of Northamptonshire, Montagu was aged 63 at his death in February 1666.
Montagu was undoubtedly returned as a burgess for Huntingdon at the behest of his father, Lord President Manchester (Sir Henry Montagu), joint lord lieutenant of the county and joint purchaser - with his brother (Sir) Sidney Montagu* - of Hinchingbrooke House, which lay just outside the borough.
While the earl of Manchester provided for each of his younger sons, Montagu derived most of his fortune from the property his wife inherited from her father, Sir Robert Baynard, who may have known Sir Edward Montagu* from his time at the Middle Temple in 1580s. On securing a command in the first Ship Money fleet of 1635, James Montagu appointed Baynard’s nephew as his lieutenant.
Baynard’s legacy was not without its problems: Montagu and his wife took over the administration of her father’s will in 1639, but within months they had difficulties in paying various bequests, and they were also prosecuted over a dispute arising from Baynard’s service as sheriff of Wiltshire in 1629-30.
Unlike Manchester, Montagu played no significant part in the Civil War. After the Restoration he claimed to have ‘suffered for the king’, but he cannot have been an active royalist, as his estates were never sequestrated, and he was not mentioned in the major generals’ list of suspected royalists in 1655-6.
Montagu fared rather worse after the Restoration, being imprisoned in king’s bench in the autumn of 1662. Although most of the inmates were debtors, he claimed to have been incarcerated ‘because, from his openness of spirit, it is surmised that he is an enemy to monarchy’.
