Big Ben is a major London monument, but its role in the novel is complex. It not only suggests tradition, but it also (with its constant gonging) doesn’t let anyone forget about the passage of time. With Big Ben, Woolf signals to the reader how important punctuality, schedules, and daily rhythms are to the tradition of English life.
You can’t help but notice the important role that time plays in the lives of all these characters. This is particularly true when we hear their memories – both beautiful and haunting. Peter can’t forget the days of Bourton and his love for Clarissa; Clarissa fears the passage of time and the inevitability of death; Septimus suffers from post-traumatic stress disorder, which prevents him from forgetting what he experienced and, in a sense, robs him of his future.
Big Ben is a big physical and aural (sound) reminder of all of these issues surrounding time. Clarissa has lived so long with the clock that she anticipates its "leaden circles dissolv[ing] in the air" (1.5). Big Ben is almost like a character with a personality: "The sound of Big Ben striking the half-hour struck out between them with extraordinary vigour, as if a young man, strong, indifferent, inconsiderate, were swinging dumb-bells this way and that" (2.92). And like a character, Big Ben seems almost to interrupt the people of London intentionally. Meanie.