Thomas, You're the Leader, sometimes called Roll Call Rap, is a song from The Great Discovery. It is the first song to be performed by Chris Madin. The song is based on Engine Rollcall, but with additional verses about the Skarloey Railway engines, the Pack and the remainder of the vehicles. A second altered music video was later made using footage from the thirteenth season. The Skarloey Railway engines, the Pack, Stanley and various other characters were cut out though, as they were not modelled in CGI at the time.