Lesson learnt, this is Christian! Also taken while on the Manchester Photographic course and I'm sure there are a few ladies in the crowd who wouldn't have minded chatting to him for a while.
Anyway this time my lesson was that you have very little time and you don't want to take too much of their time but make sure you have the camera settings right for what you want to do. In this case we were using AI Servo (on Canons not sure what the Nikon equivalent is) and I didn't spot the refocusing as I recomposed after focusing on his eyes. Darn.
Still number two in the bag