Born at Withcote in Leicestershire around 1620, Henry Smith studied at Oxford and Linclon's Inn, and was elected recruiter MP for Leicestershire in November 1645. He was associated politically with Henry Marten and the republicans. Smith was a member or several committees in the Purged Parliament, and in January 1649 was appointed a commissioner on the High Court of Justice. He attended every session of the King's trial and was one of the 59 signatories of the death warrant.
In 1651, Smith served as a major of horse in the forces raised by Lord Grey of Groby to defend the Midlands against the invasion by Charles II and the Scots. In 1658, he was appointed governor of Hull and earned the praise of the Council of State by uncovering a plot by the Royalist conspirator Sir Henry Slingsby to subvert officers of the Hull garrison and betray the town to Charles II.
At the Restoration, Smith surrendered to the authorities and was brought to trial as a regicide in October 1660. He pleaded youthful ignorance and "bad influence". Although sentenced to death, he was allowed to appeal and the sentence was commuted to life imprisonment. Smith was held at the Tower of London until 1664, then transported to Jersey, where he is presumed to have died around 1668.
References:
K. R. Gardiner and D. L. Gardiner, Henry Smith, Oxford DNB, 2004