It’s a good idea during an interview to refer to the interviewer by their first name. There is no need to call them Mr or Mrs. Simply refer to them by their first name and write it on a piece of paper in front of you just in case you forget as that can happen when nerves are at play. It creates a warm energy between you. In the mind of the audience it appears you are on good friendly terms with someone who is very influential – therefore if they like the interviewer then it’s likely they’ll like you too.