After an appeal or the second appeal provided in regulation 12 has been rejected, a person to whom these regulations apply, may apply for revision to such superior authority as may be prescribed in the regulations regulating his condition of service:
Provided that the powers of revision shall be exercised only─
(a) if the appellate authority is one other than Chancellor; and
(b) on the ground of material irregularity in the proceedings of the inquiry officer 103 or appellate authority, or on the discovery of new and important matter of evidence, which after the exercise of diligence was not within the knowledge of the petitioner, or could not be produced by him when the orders were passed against him or on account of some mistake or error on the face of the record.