Tesco interview questions

I applied online doing the usual online questionnaire that comes with applying to work at a supermarket. I passed that by selecting the obvious options and swaying towards the customer service answers. I then got a call from a Checkout Manager and arranged a 'small interview'. That is exactly what it was, a checkout manager and I went into a small office where she asked me a couple of questions in an informal setting. (The questions that were asked were all in a book and were obviously asked to every single person entering Tesco country-wide). It was a while ago now but roughly: Give me an example of when you provided excellent customer service...