I have John Lewis JLBIOS602 which has begun to misbehave.
The oven is overheating and appears not to be switching off. The heating element behind the fan can be seen glowing red even after the oven has switched off. I did a test by running the oven in defrost mode and noted that the oven was heating up. I set the oven to switch off on the timer after five minutes. As the time expired the fan switched off, but I noted that the fan element continued to glow red and only switched off when I isolated the oven at the mains.