Noel Coward learns a lesson in privilege

I do not have any documentation for this anecdote. It is one that I remember Noel Coward tell on Dick Cavett's late night talk show on ABC in the early 70s.

When Fiorello LaGuardia was mayor of New York City, Coward attended the opening night performance of a play involving a close friend of his. After the performance, he went to the telegraph office in Times Square to send the friend a mock congratulatory telegram. He signed the telegram "Fiorello LaGuardia". When the clerk for Western Union saw the signature, he told Coward that there was a company policy requiring that all telegrams be signed by the sender. So, Coward crossed out LaGuardia's name and wrote down "Noel Coward" in its place. The clerk then said to Coward that the problem was not that he had used LaGuardia's name but that he had not signed his own name. Coward told the clerk, "But I am Noel Coward". And the clerk said to him. "In that case, you can sign it Fiorello Laguardia"