Vane was instrumental in the 1641 impeachment and execution of the Earl of Strafford, a member of the Privy Council. Vane discovered some confidential notes his father had made of a council meeting, and passed them to John Pym. The wording in those notes could be interpreted to mean that Strafford had proposed that Charles use the Irish Army to subjugate England. The evidence against Strafford was weak, and the impeachment failed. Pym consequently orchestrated the passage of a bill of attainder against Strafford, who was then executed in May 1641. The illicit means by which Pym acquired the notes caused a rift between the Vanes that healed only when the elder Vane eventually came to oppose the king.