I think that they were seeing how you react to the thought that signalling school needs effort and isn't 9/12 weeks holiday in a hotel! Although probably not officially part of the interview its good showing people around to be able to see how people react to others, and how they will behave in the workplace. Sounds like it went well - what you have to remember if you are not successful, is that it doesn't mean that you were rubbish. It means that someone presented better on the day. So while its fresh - think about if you could have improved any answers and store that information for the future. Hopefully its not required - just call it insurance!