I do believe in being on time for meetings. It gives a bad impression to be late. With new prospects and even with clients, they can be left feeling very unimpressed by a late show.
Sometimes we are late due to circumstances beyond our control. We are stuck on the road with a serious hold-up. There has been an accident. We might be let down by public transport. Our train has broken down. In those case we need to let the person we are meeting know in good time what has gone wrong and why we will not be there when we said we would.
Someone who does work for us at home was very late the other day. In fact we had almost given up on her, were noting her other inadequacies and talking about sacking her. Eventually she turned up just in time to save herself from getting the bullet, at least for now. However she failed to call to advise she was running late, even though her mobile (cell) is rarely neglected during her time with us; one of the little grouses we have about her. That is the point. Being late will be aggregated with other transgressions, real or imagined.
A late show can cut off future business. Be there, or at least apologise in advance if you can’t.