In relation to the manner of performance and the steps to be taken in the event of defective performance, regard shall be had to the law of the country in which performance takes place.
Lex loci solutionis supplements lex contractus for factual considerations such as closing times.
In the case at issue, between parties, a notice had to be served ‘by close of business’. A relevant fax transmission started at 5:54 PM and ended at 6:02 PM. Close of business by sender, it was alleged, was understood to be 7 PM. Recipient claimed COB was 5 PM. Blair J in para 147 ff justifiably points to the intention of flexibility behind the notion of COB: had parties wanted a precise cut-off time, they would and should have specified it. The High Court therefore relied on the (little) evidence given as to COB and accepted that in the modern world of commercial banking and even leaving aside the near non-existence of closing hours for investment bankers and the like, more or less 7 PM should be considered COB. (It was specifically stated that no precedent value can be attached to that time slot).
(Handbook of) EU Private international law, 2nd ed. 2016, Chapter 3.