Tell us about an experience in which you had to use tact?

Tact and diplomacy are important qualities in retail banking - the customer is (almost!) always right. You may have to tell an account holder diplomatically why they can't have a loan for example, without provoking them into moving their account elsewhere.
To answer this type of question, think through everything you have done in the last five years - school, university, sports, clubs, societies, travel, vacation jobs etc. and try to think of situations where you had to demonstrate this and other qualities - do this before your interview.

If you have completed a number of employer application forms, then you should already have done this as this type of question is now common on application forms.