However, all acts and ordinances passed by Parliament during the Civil War and Interregnum did not have royal assent, so they were deemed to be null and void following the Restoration of the monarchy in 1660.
Shortly after his death the Rump Parliament passed a series of acts which established the Commonwealth (see High Court of Justice for the trial of Charles I).
The execution of Charles I was delayed until later in the day on 30 January than had originally been planned, so that the House of Commons could pass an emergency act, the "Act prohibiting the proclaiming any person to be King of England or Ireland, or the Dominions thereof", that made it an offence to proclaim a new King, and to declare the representatives of the people, the House of Commons, as the source of all just power.
Although the Act ceased to have effect from 1660, the treason consisting of inviting foreigners to invade England or Ireland was soon copied in the Sedition Act 1661, which made it treason "to move or stirr any Foreiner or Strangers with force to invade this Realme or any other His Majesties Dominions or Countreys being under His Majesties Obeysance".
Although no longer treason today, this remains an offence under the Treason Felony Act 1848, which makes it a crime punishable with life imprisonment "to move or stir any foreigner or stranger with force to invade the United Kingdom or any other of her Majesty's dominions or countries under the obeisance of her Majesty".