55.—(1) For the purposes of these rules “costs” means costs and expenses recoverable before the Supreme Court of England and Wales, the Court of Session or the Supreme Court of Northern Ireland.
(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 (1), (2) or (3) 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 Supreme Court or a taxing officer of the Supreme Court of Northern Ireland or by the Auditor of the Court of Session.
(4) Unless the Tribunal otherwise directs, an order made pursuant to paragraphs (1) and (2) may be made in the decision, if the parties so consent, or immediately following delivery of the decision.
(5) The power to award costs pursuant to paragraphs (1) to (3) includes the power to direct any party to pay to the Tribunal such sum as may be appropriate in reimbursement of any costs incurred by the Tribunal in connection with the summoning or citation of witnesses or the instruction of experts on the Tribunal’s behalf. Any sum due as a result of such a direction may be recovered by the Tribunal as a civil debt due to the Tribunal.