As I was writing this post to beg for help I realised the answer, but still it is bull. Just a post to help out any other confused should out there. When updating my British mbp to 10.11.5 it switched my default keyboard to US. Which means the usual way to get to # and some of the other symbols on shift above the number keys did not correspond. Do not know why this happens. Surprise surprise it's another bug in Apple's software. Absolute joke. My computer infuriates me these days because I remember what they used to be like. Absolutely rock solid. They don't drive me insane enough to contemplate windows again. But its the feeling of knowing how downhill they have gone.