"(iv) At each end of the spectrum there will be the cases where it is obvious which side would have won had the substantial issues been fought to a conclusion. In between the position will in different degrees, be less clear. How far the court would be prepared to look into previously unresolved substantive issues, will depend on the circumstances of the particular case, not least the amount of costs at stake and the conduct of the parties; (v) In the absence of good reason to make any such order, the fallback is to make no order as to costs."