A London goldsmith and congregationalist, Barkstead joined Parliament's army as a captain of foot in Colonel Venn's regiment at the start of the civil wars. He was governor of Reading from July 1644 until January 1647, when he was commissioned colonel of an infantry regiment in the New Model Army. Barkstead's regiment occupied Whitehall during the political disturbances of January 1648 and helped secure Southwark against Royalist insurgents in May. In June 1648, Barkstead marched a brigade of infantry 50 miles from London in 48 hours to join Lord-General Fairfax at the siege of Colchester. In January 1649, Barkstead was one of the hard core of Army officers who sat on the High Court of Justice and signed the King's death warrant.
During the 1650s, Barkstead worked closely with Cromwell's spymaster John Thurloe in intelligence work and in maintaining London's security. In 1652, he was appointed Lieutenant of the Tower of London. Cromwell praised Barkstead's efficiency, but his enemies accused him of treating prisoners in the Tower harshly and of amassing a large fortune by charging extortionate fees. He was elected MP for Colchester in the First Protectorate Parliament, and In 1655 became military governor of Westminster and Middlesex during the Rule of the Major-Generals. As deputy to Philip Skippon, Barkstead was also effectively Major-General for the City of London. Barkstead was zealous in suppressing immorality and ungodliness in the City and surrounding districts. He was knighted by Cromwell in January 1656, sat as MP for Middlesex in the Second Protectorate Parliament and was appointed to Cromwell's Upper House.
Barkstead was elected to the Third Protectorate Parliament under Richard Cromwell, but came under attack for his conduct as Lieutenant of the Tower. When the Purged Parliament was recalled in 1659, Barkstead was dismissed from office. At the Restoration, he fled to Germany where he was welcomed and given the freedom of the Lutheran city of Hanau. However, when he travelled to the Netherlands to meet his wife, he was arrested by the English ambassador Sir George Downing and returned to England to be brought to trial as a Regicide. He was hanged, drawn and quartered at Tyburn in April 1662.
References:
Christopher Durston, John Barkstead, Oxford DNB, 2004
Christopher Durston, Cromwell's Major-Generals, 2001