Dear Miss Manners:
Frequently, people prefer to be known by a middle name. I happened to find that someone I will be meeting prefers to be known by his middle name. The problem is that he has been knighted. As a further complication, I know that he is a retired army officer. Thus, he is (I will substitute names) Col. Sir John Philip Smith.
Would it be better to call him "Sir John" or "Sir Philip"? He will probably introduce himself to me as "Philip Smith," but I feel that I should know the appropriate form of address.
Chances are, Miss Manners is guessing, that the gentleman did not interrupt the ceremony to say to the queen, "Oh, call me Phil; all my friends do." Thus, when you address him formally, you call him Sir John. It is then up to him, if he wishes, to say "Oh, call me Phil . . ."
I did not know that, Miss Manners!