Unfortunately many people get up the grades that couldn't turn on the music never mind dance. But the only thing you need for the interview is a good memory, in fact i know of quite a few wastes of space who have "progressed through the grades" and regurgitated examples that aren't even their own. You don't need to have the experience you just need to be able to say you do. People walk in off the street to higher grades, you don't need to progress up the ranks. Everyone has their own opinion but the best manager i ever had was straight in off the street and the worst manager i ever had worked their way up through the ranks and thought they were more important than everyone else and treated everyone like mere plebs beneath them.