The song Shallow has an interesting writing history. The rest of the Deadwing album was recorded, sent to the record company. They wrote that they couldn’t play any of these songs on American rock radio, they needed one more song for 4 minutes that would be a doorway for listeners. So Steven Wilson composed the song Shallow.
Now, he likes it, but he feels some insincerity knowing the writing history. Since the 2006 Porcupine Tree tour, it has never been performed live.
Steven Wilson told this in an interview with Rob Moore.