"Where a certificate is granted under this section, then, if in any subsequent proceedings before the court or the comptroller for infringement of the patent concerned or for revocation of the patent a final order or judgment or interlocutor is made or given in favour of the party relying on the validity of the patent as found in the earlier proceedings, that party shall, unless the court or the comptroller otherwise directs, be entitled to his costs or expenses as between solicitor and own client (other than the costs or expenses of any appeal in the subsequent proceedings)."
"(3) Subject to paragraph (2), costs are to be assessed on the indemnity basis but are to be presumed – "(a) to have been reasonably incurred if they were incurred with the express or implied approval of the client; "(b) to be reasonable in amount if their amount was expressly or impliedly approved by the client; "(c) to have been unreasonably incurred if – "(i) they are of an unusual nature or amount; and "(ii) the solicitor did not tell the client that as a result the costs might not be recovered from the other party."
"In Otto and Steel, solicitor and client costs were refused on the ground that the validity of the patent was attacked on new grounds [citingFlour Oxidising v Hutchison] although it is unlikely that that case will be followed at the present time, save in exceptional circumstances."