Mark could do an instrumental cover of an ABBA song if he wanted to, not singing though. Mike Oldfield has covered ABBA's Arrival on his album QE2. Benny & Bjorn are amazing song writers and musicians, I asked Guy if they had met them, and it seems like they have!! Agnetha and Frida are 2 of the greatest singers ever. Don't forget Guy had written for Frida too.