Fantastic, thanks Mike that's exactly what I was after. I found my answer...
5.1.6 Inward Gauging. For inward gauging the value of a shot will be decided by the edge of the shot hole nearest the centre of the target as determined by the use of the gauge. When the flange of the gauge touches the line, the higher value will be credited. Shots outside the scoring rings have no value.
I was pretty certain I was right in scoring them zero, nice to have it confirmed in black and white. You've set my mind at ease.
cheers
Andy