Fifteen minutes is the established length of time that a host need delay his/her dinner for a late guest. To wait longer would be showing rudeness to the rest for the sake of one. When the latecomer finally arrives he must go directly to the host and apologize for being late. The host should not tear a strip off the late guest but should say something polite such as, 'I'm sorry to hear the traffic was so bad. I was sure you wouldn't have wanted us to wait much longer for dinner.' The latecomer is served whichever course is being eaten at the time he arrives. If it's dessert, he is served a plate of the main course if there is any left.