21 It cannot be doubted that the arbitrator was, in arriving at his decision on the issue of costs, entitled to take into account the fact that the builder had not, at the appropriate time, claimed time extensions or time extension costs, and that, when it did make these claims during the course of the arbitration, it failed, for some time, adequately to support them. His error (and it was common cause, on the hearing of the appeal, that he was in error) was in misunderstanding the applicable legal principles. However, the Judge below, in considering that the builder should be regarded as the successful party, did not mention these considerations. Rather, his Honour said, as will be apparent from the extract from his reasons quoted above, that it did not appear from the arbitrator's review of the issues that the builder was instrumental in advancing extravagant claims. While that may be so, the arbitrator certainly considered that the builder had advanced claims which need never have been the subject of the arbitration proceedings had they been made, and appropriately supported, "during the normal course of the contract". In making the comments that the builder did not appear to have advanced any extravagant claims and that it "was obliged to proceed to arbitration in order to recover moneys alleged to be due to ... [it]" his Honour appears to have overlooked this consideration, which had been found by the arbitrator (not unreasonably in my respectful opinion) to have been important in considering what should be done about the costs of the application.