There are 3 temp senders on the R/H side of the head just infront of the dizzy, they are all the same, one is for your temp gauge and the other 2 go to the idle controller thingy screwed to the back of your centre console. Swap the wires around, one sensor might be a bit out so giving you a false reading. Give them a good clean too.
Although when I took mine to the MOT station this weekend i was sat in a lot of traffic, mine too crept up to 3/4, i checked the oil temp and it showed 110 deg. fan was cutting in and out though.