"I didn't really know how to work with composers, so it was much more about records in the beginning," says Boyle. As the twisty noir ends, Ewan McGregor, knife stuck through his chest, grins sublimely as his blood drips down onto the stacks of money stashed between the floorboards. He grins, knowing his double-cross worked, as the soundtrack booms with Andy Williams corny old uplifting classic, "Happy Heart."
"You don't want to do anything too obvious. You're trying to find an extra irony, an extra delight," Boyle says. "That was a big track for my dad. He loved crooners. And, God's honest truth, we were hanging out in Glasgow where we did most of the shooting, and as we got into a black cab, the driver was playing it. That moment, as you get into the cab, you go, 'That's the end of the film.' You know. It's perfect. Despite what you're seeing, inside he's feeling, 'It's my happy heart,' and singing loud as he can."