Switched off the CH last night just before I went to bed.
13.5 togs of duvet determine that I don't need it running overnight.
I don't run the heating when I get up in the morning as less than half an hour passes between the alarm going off and me leaving the house.
I get home this afternoon to find the place like a tropical greenhouse, with the first palm starting to sprout from behind the skirting board.
Turns out that I hadn't switched off last night. Only pushed the slider switch to the next detent yclept 'PROG'.
It transpires the PROG 4 was running (I don't even know what PROG 4 is as I never programme the heating) when I came home this afternoon.