Westminster assembly, under the pseudonym of "Martin Marpriest", who was represented as the son of Martin Marprelate, the antagonist of the Elizabethan bishops. The series of tracts he issued under this name, of which the chief are The Arraignment of Mr. Persecution, Martin's Echo, and A Sacred Synodical Decretal, were published clandestinely in 1646, with fantastic printers' names appended to them. The Decretal is a supposed order of the Westminster assembly for the author's arrest, purporting to be "printed by Martin Claw-Clergy, printer to the reverend Assembly of Divines, for Bartholomew Bang-priest, and are to be sold at his shop in Toleration Street, at the sign of the Subjects' Liberty, right opposite to Persecuting Court". Prynne denounced these tracts to parliament as the quintessence of scurrility and blasphemy demanding the punishment of the writer, whom he supposed to be Henry Robinson. Overton's authorship was suspected, but could not be proven. He did not own his responsibility till 1649, when the assembly of divines had come to an end. Against the Lords In 1646, Overton, who had been concerned in printing some of Lilburne's pamphlets, took up his case against the Lords, and published An Alarum to the House of Lords against their Insolent Usurpation of the common Liberties and Rights of this Nation, manifested in their Attempts against Lieutenant-colonel John Lilburne, An Alarum... 4to, 1646. For this he was arrested by order of the house on 11 August 1646 and, refusing to acknowledge their jurisdiction, was committed to Newgate. Yet in spite of his confinement, he contrived to publish a narrative of his arrest, entitled A Defiance against all Arbitrary Usurpations, and a still more violent attack on the peers, called An Arrow shot from the Prison of Newgate into the Prerogative Bowels of the Arbitrary House of Lords. His wife Mary and his brother Thomas were also imprisoned for similar offences. The New Model Army took up the cause of Overton and his fellow prisoners, and required that they should be either legally tried or released. He was unconditionally released on 16 September 1647. This imprisonment did not diminish Overton's democratic zeal. He had a great share in promoting the petition of the London levellers on 11 September 1648. He was also one of those who presented to Fairfax on 28 December 1648 the Plea for Common Right and Freedom, a protest against the alterations made by the council