After James's death in 1625, Constable found an ally in Sir Thomas Wentworth, the future Earl of Stafford.
In 1630 Constable fell into considerable debt, and was forced to sell his estates, with plans to move to New England.
Constable returned to England in 1641 and, with the support of his brother-in-law Lord Ferdinando Fairfax, was elected MP for Knaresborough, Yorkshire.
After the King had been executed at the Banqueting House, Whitehall, he sat on the Council of State and attended many parliamentary committees concerned with military matters.
After the restoration of the Monarchy in 1660, his body was exhumed from the abbey and re-interred in a communal burial pit in St Margaret's Churchyard, Westminster.