Recently I received a letter from Mr. A. H. Maclean, who travelled north by the 11-coach "Flying Scotsman", and remarked that the train "was filled to capacity and we were forced to stand in the corridor"—for nearly 270 miles— [...] Obviously the diesel was working well below her load capacity on this schedule and some addition to the formation ought to have been made to accommodate the standees.
Source: wiktionary