‘I have always been a quarter of an hour before my time, and it has
made a man of me.’
L O R D N E L S O N
Failing to be punctual is the height of bad manners because it disregards the value of other people’s time. By being late you are effectively forcing the people you are meeting to waste their time; hanging around waiting for someone is deeply frustrating. By being late, you will always arrive at your rendezvous on the wrong foot; flustered, apologetic, disadvantaged. Conversely, being punctual always scores bonus points. You will come across as someone who cares about other people, and is efficient, organised and reliable.
Given the vagaries of transport systems, the tendencies of meetings to over-run, the unpredictable emergencies of modern life, you cannot expect to be invariably punctual. If you see that you’re going to be late, pre-empt the fallout, and call the person you’re meeting to tell them, with profuse apologies, that you are delayed. If the situation looks out of control (total rail shutdown, terrorist alert, home emergency), inform them immediately and reschedule.