Just think though Ratty, the reason the body takes a few days to get into Ketosis is your using up all your supplies that you've stored already, since you've had 9 days without food, and just 2 sausages it shouldnt take you as long to get back into it!
Its hard when you fall off the wagon but we are all human, and eating is natural to us, your body was probably just craving that extra something to push the cold away.
Just get back on the wagon and put this down as a little hick up, it shouldnt effect the scales too much this week