why was george not able to know that it was half past three and not eight thirty in the morning ?

George runs out into the street because he thinks he is late. He finds the streets dark and empty. He knows something isn't right,

He ran hard for a quarter of a mile, and at the end of that distance it began to be borne in upon him as a strange and curious thing that there were so few people about, and that there were no shops open. It was certainly a very dark and foggy morning....