User blog comment:Rassilon of Old/Ep. 124 "Performance" discussion/@comment-4803933-20120406015533/@comment-4454131-20120406204119

well, it's been 4 years so maybe some of the performers he knew aren't there anymore just like some might be new people he doesn't know. I don't think it's been mentioned how well he knew the others. Also, you have to wonder how Artemis doesn't recognise Robin's voice when he talks to her at school. (I'm assuming that time he took a picture of her on her first day wasn't the only time)