Strafford's trial began on 22 March 1641 with John Pym leading the prosecution. Strafford defended himself so well that his alleged treason could not be proved. When it looked as if he might be acquitted, Pym and his supporters resorted to a Bill of attainder.

This petition from Strafford to the House of Lords was in response to the Bill of Attainder. The final page is signed in the right hand corner by Strafford.