"(1) For the purposes of these rules "costs" means costs and expenses recoverable in proceedings before the Senior Courts of England and Wales ... (2) The Tribunal may at its discretion, subject to paragraph (3), at any stage of the proceedings make any order it thinks fit in relation to the payment of costs by one party to another in respect of the whole or part of the proceedings and in determining how much the party is required to pay, the Tribunal may take account of the conduct of all parties in relation to the proceedings. (3) Any party against whom an order for costs is made shall, if the Tribunal so directs, pay to any other party a lump sum by way of costs, or all or such proportion of the costs as may be just. The Tribunal may assess the sum to be paid pursuant to any order under paragraph (2) or may direct that it be assessed by the President, a chairman or the Registrar, or dealt with by the detailed assessment of a costs officer of the Senior Courts ..."