Whistler’s father was a younger son in a modest gentry family with lands in Berkshire and Oxfordshire.
Whistler delivered his maiden speech on the subject of the disputed Cambridgeshire election on 5 Mar. 1624.
Re-elected to Charles’s first Parliament, Whistler, amid fears that the session would have to be adjourned to avoid the plague epidemic in the capital, recommended on the second day of business that the House should not investigate disputed returns but accept them without question as time was so short (21 June 1625).
In 1626 Whistler’s committee appointments included the committee for privileges (9 Feb.) and a bill to preserve the rights of ecclesiastical patrons (14 Feb.); he was also added to the committee to consider the bill against secret inquisitions on 17 February.
Whistler succeeded Wentworth as Oxford’s recorder in 1627 and was elected as the senior Member in 1628. In contrast to his cautious stance in the previous Parliament, he spoke out twice on arbitrary imprisonment. On 26 Mar., and again two days later, he opened the debate in a committee of the whole House with a disquisition on the question ‘whether a commitment by His Majesty or his Privy Council containing no cause be such that the judges of the King’s Bench may deliver them?’ and proposed a conference with the Lords.
In 1629 the corporation of Oxford gave Whistler 20 marks on the occasion of his readership at Gray’s Inn.
