When his father died in 1601, Peregrine inherited a manor in Norfolk and the reversion of Willoughby House in London.
Prince Henry died at the end of the year, and in the fall of 1613, Peregrine went abroad again and fought another duel with Lord Norreys, much to the displeasure of King James.
In 1614, he contested Lincolnshire with the courtier Sir Thomas Monson and was returned as its junior knight of the shire to the Addled Parliament.
By the end of the year, he was suffering from a dangerous illness and his death was rumored, providing Lord Norreys with an opportunity for reconciliation.
He volunteered to join the relief of the Palatinate led by Sir Horace Vere in 1620, but did not actually go abroad; in the following year, he was made a justice of the peace for the Parts of Lindsey.
He was subsequently recalled and appointed a colonel of foot, commanding a regiment in the disastrous Île de Ré expedition.