Stephen Sackur speaks to an Irish writer whose intense, lyrical novels have won him awards, acclaim and millions of readers around the world. Colm Tóibín isn't 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 of loss, mourning and exile which might suggest a dark, brooding presence - but how close is that to the real Colm Tóibín?