Stephen Sackur speaks to an Irish writer whose intense, lyrical novels have won him awards, acclaim and most importantly millions of readers around the world. Colm Tóibín is not so much a flamboyant storyteller, he is more an acute observer of character and the deepest human feelings. There are recurring themes in his work - loss, mourning, exile, which might suggest a dark, brooding presence - but how close is that to the real Colm Tóibín?