Though Poley spent 20 years of his life as a Cambridge don, his aspirations lay at Court. As an undergraduate, he wrote to the courtier Endymion Porter†:
The pleasure I find in this contemplative life is, besides my quiet studies, especially the knowledge of the affairs of my noble friends, with the remembrance of that practical life I lived at London and elsewhere of late, to which if I return, I hope I shall be better able to serve you than in this dull place.
Early in 1628, Poley and his cousin Henry Jermyn* secured a monopoly of a new treatment for foot-rot in sheep. Two months later Poley was returned to the Commons for Wilton, seat of the 3rd earl of Pembroke, presumably at the nomination of his brother-in-law, (Sir) Humphrey May*. He was cited only once in the records of the Parliament, during a protracted debate of 31 May about the details of the subsidy bill, when he declared that Oxford deserved precedence only over the suburbs of Cambridge.
On 8 Aug. 1628 Poley was licensed to travel for three years; he had probably already left the country as a member of the earl of Carlisle’s embassy to Lorraine, Italy, Germany and Brussels, during which travels he met Sir Thomas Roe*, who found his conversation ‘sweet, gentle and equal’. He left no trace upon the 1629 parliamentary session, and soon after the dissolution he accompanied Roe to the Baltic ‘in an unprofitable journey, where he saw many courts’.
Poley secured a Court position in the Household of the Prince of Wales in 1638. A royalist during the Civil War, he was deprived of his Cambridge fellowship by Parliament. He acted as a diplomatic messenger for the royalist cause, and accompanied his master to Scotland in 1650.