eight o'clock
Mails came from the country in some instances with the letters unsorted , thus increasing the difficulties of the situation . The struggle was all the more severe that preparations for the night despatch were begun with a jaded force , some of the men having already been twenty-six and twenty-eight hours at work . Moreover , frost and fog prevailed at the time , and that not only delayed trains and the arrival of mails , but penetrated the building so that the labour was performed in a depressing atmosphere . To meet the emergency , at least in part , the despatch of the usual eight o'clock mail was delayed for that night fifty minutes . As in actual war an hour 's delay may be fraught with tremendous issues for good or ill , so this brief postal delay permitted the despatch of an enormous amount of correspondence that would have otherwise been left over to the following day . Usually the despatch of the evening mail leaves the vast sorting-hall in serene repose , with clean and empty tables ; but on the night of this great battle -- which has to be re-fought every Christmas -- the embarrassment did not cease with the despatch of the evening mail . Correspondence continued to flow on in as great a volume as before .