We have also seen a 4 seasons tribute act on P&O that were excellent, but mainly because we love the music, however I have no idea what their names were.
We also saw Grease on Indy and again, because we know and love the music, it was very enjoyable, but the day we saw it, some of the cast seemed to be having an off day, and they struggled with the continuity. On the same cruise they had a Beatles tribute act in the theatre, and we have also seen the same group on P&O. It seems that many of the same acts do the rounds of most of the ships that cruise from Southampton.