Got the problem sorted

I took off the stat housing to find the clip in place but the thermostat had some movement. So i removed the clip and thermostat, to find that the rubber seal had moved away from where the thermostat sits and that half the seal had moved away from the lip and was sitting in the elbow. so the water was passing around the thermostat. i'm not sure how on earth the seal managed to move away but when i placed it back i put some sealant around the seal and re fitted the stat. all seems fine and is running to temp perfect. so a cheap fix for me but i hope it doesn't happen again.

Thanks again for all your help