I was delighted to discover Rosanne Cash was following me on Twitter. Perhaps better known in America, Johnny Cash's daughter is a star in her own right. Musically gifted, liberal and sharply intelligent, an aura of celebrity hangs around her. Proof of this is the blue tick beside her Twitter profile, the micro-blogging website's indicator of fame. I lack one myself. Several years back I was a newbie on the site, garnering followers at a snail's pace, when late one night @rosannecash tweeted me a big "Hellooooooo, Brian!" Wow, that's Rosanne Cash, I thought, scion of the legendary Man in Black. My tweets, mundane as they were, had somehow caught her eye. Maybe I'm more interesting than I allow myself to think, I allowed myself to think. Playing it cool I replied with a simple: "Hi, Rosanne, good to meet you on here." I told one or two friends - casually, mind you - that I had joined Twitter and that, by the way, Rosanne Cash had started to...