I've met with Jhon in Madrid and he's told me his method. He's creative and establishes a rapport with his subjects so that when he takes their photograph they already know him. And he's also a very generous host! A tu salud, amigo!
The funny thing: I didn't see the man when I took this photograph. I was coming out of the metro station by Plaza Catalunya when I saw the young couple. Fortunately, I had metered and set the EV in the camera so all I had to do was virtually point, focus and shoot. Much later, when I scanned the slide, I saw the old man looking at me in disapproval...