Any person who, immediately before the appointed day, is an advocate entitled to practise in the High Court of Assam, Nagaland, Meghalaya, Manipur, Tripura and Mizoram and was authorised to appear or to act in any proceedings transferred from the said High Court to the common High Court under section 26 shall have the right to appear or to act, as the case may be, in the common High Court in relation to those proceedings.