Imagine you’re a sausage. You are in a frying pan, happily sizzling away with other like-minded sausages. Then one of them starts to tell you about tomato ketchup. You refuse to believe your friend’s stories but later you find yourself being dipped head first into that tangy, tomatoey joy. And then you realise that yes – ketchup is true. Watching James Campbell is a bit like that. But there aren’t any sausages involved. Or ketchup.