I don't think he did, if you notice Simon was checking a list to see what song was next & he says something to Jamie then starts singing, Jamie looks amused because I think he wasn't ready so Simon sang it for him until he could take over. To me Jamie's reaction was more a sort of "Hey that's my bit..."!! Jamie & Simon are both lovely guys & extremely clever & talented.
They are indeedy! Yep they're all West Enders. Simon Lipkin is in Rock of Ages, Owen Visser is one of the sound team at Rock of Ages and Jamie Muscato used to be in Rock of Ages and is in The Light Princess from September.
