Lord Caversham is Lord Goring's father. He provides a generational foil to Lord Goring, much as Lady Markby does to Lady Chiltern. An old-fashioned public servant, Lord Caversham believes that politics is the noblest profession. He is often unknowingly ironic as he compares his son to Sir Robert:
Look where your friend Robert Chiltern has got to by probity, hard work, and a sensible marriage with a good woman. Why don't you imitate him, sir? Why don't you take him for your model? (3.53)
Of course, we know that at this very moment Lord Goring is scrambling to save said marriage, due to Sir Robert's being much less than a model. A little dramatic irony shows that perhaps Lord Caversham is not as wise as he first seems.