Changing derby leagues isn’t always as simple as dropping a Facebook message to your new team,  rocking up with your skates and slotting into your accustomed position on the track.  An expatriated player herself, Cat Cholera interviews two globe-trotting former Perth Roller Derby  players, Dame Edna Haemorrhage and Lorrae Evans, exploring the ins and outs of changing countries,  languages and cultures to play roller derby around the world.