Jules001, Peter is a comedy actor, if the show had wanted Peter to be in Victorian dress, the production team would have made sure there was a costume available in his size.
The bird costume may have been Peter's idea, but there is no way the production team would leave it to a guest to supply their own costume.
Peter was mostly there ( I think ) to promote the children's animation series he provides some voices for.
The series is "Roary the Racing Car" on FIVE around 7.20am each morning.