I'm fairly sure BJ played 'We Will Rock You' at Donington in '87. Can't remember them covering any other Quuen songs though.

Brian May also appeared with BJ at the Brits one year, performing 'I'll Sleep When I'm Dead' along with Dina Carroll (I think it was her, could be wrong)

Also remember a quote from Jon/Richie/David from years back, where after performing with BJ at Wembley Arena, Brian May had told them to remember to enjoy the moment. He said they reminded him of Queen, in that they also forgot to enjoy the sucess. Or something along those lines. Memory's not what it was.