Musicians don't come much bigger or more successful than Brian Johnson and Mark Knopfler - lead singers of AC/DC and Dire Straits respectively. These two legends of rock have sold a staggering 300 million records between them, toured for more than 40 years and have each left their own indelible mark on our cultural history.Now, after a lifetime in music, Brian and Mark are taking a moment to reflect by sharing their incredible knowledge, experience and insights with each other - and the world.