According to the email I received, dress code is smart casual. I find it strange to go to an interview in anything other than a suit, but obviously this isn't what they want. What sort of attire did people find to be go on the day?
For smart casual, I would go with the crisp, pressed long-sleeved shirt coupled with black pants and leather loafers (or other "business shoes").
Would they actually fault you for wearing a suit? I doubt it.