The arbitration, as instructed by the Crown, was based on legal argument and documentation, and led to the Cornwall Submarine Mines Act 1858. The Officers of the Duchy, based on its researches, made this submission:  However, the term 'county palatine' appears not to have been used historically of Cornwall, and the duchy did not have as much autonomy as the County Palatine of Durham, which was ruled by the Prince-Bishop of Durham. However, whilst not specifically called a county palatine, the Officers of the Duchy made the observation (Duchy Preliminary Statement – Cornish Foreshore Dispute 1856):  The Dukes also had their own escheators in Cornwall, and it is deserving of notice that in the saving clause of the Act of Escheators, 1 Henry VIII., c. 8, s. 5 (as is the case in numerous other acts of Parliament), the Duchy of Cornwall is classed with counties undoubtedly palatinate. In 1974, a group has claimed to be a revived Cornish Stannary Parliament and have the ancient right of Cornish tin-miners' assemblies to veto legislation from Westminster, although it opposed the Duchy of Cornwall. In 1977 the Plaid Cymru MP Dafydd Wigley in Parliament asked the Attorney General for England and Wales, Samuel Silkin, if he would provide the date upon which enactments of the Charter of Pardon of 1508 were rescinded. A letter in reply, received from the Lord Chancellor on 14 May 1977 and now held at the National Library of Wales, stated that the charter had never been formally withdrawn or amended, however that "no doubt has ever been expressed" that Parliament could legislate for the stannaries without the need to seek the consent of the stannators. The group seem to have been inactive since 2008. An early campaign for an independent Cornwall was put forward during the first English Civil War by Sir Richard Grenville, 1st Baronet. He tried to use "Cornish particularist sentiment" to gather support for the Royalist cause. The Cornish were fighting for their Royalist privileges, notably the Duchy and Stannaries and he put a plan to the Prince which would, if implemented, have created a semi-independent Cornwall. In contrast to the arguments that Cornwall is already "de jure" autonomous, thanks to the Duchy and Stannary parliament, various ongoing political movements are seeking to "change" Cornwall's constitutional status.