"(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. …"