BBC 6 music, an entirely digital radio station hits 2 million listeners. It's a free form modern rock station but it's only on digital FM & online. 

BBC Radio 1 has attempted to chase a younger audience but their average listener age is 33.7.  Ratings are down likely because the 33.7 year olds don't like hearing announcers who attempt to appeal to 15 year olds.  Could it be that "pop music" really appeals to all ages now? 

http://www.theguardian.com/media/2014/oct/23/bbc-radio-6-music-lauren-laverne-nick-grimshaw