I've read that he didn't put a light on because he didn't know where the switch was. It wasn't obvious to him, perhaps it was low down or high up. Perhaps during the party the light was already on?
Tortoise,
I'll guess he knew where the light switch was but never bothered with it. Later he rationalizes his decision as we are all prone to do.
Here is how I think FW was operating, he opens the door and looks in, if he can see something unusual then a light is required else its a negative?
On a previous visit similar behavior must surely have played out, two switches to select from and a host to ask?
Here is another way of putting it, FW never said the wine-cellar never had a light, so he never bothered looking for one.
If as you suggest FW does not know where the light switch is located then he must be flying on his previous experience as the R's butler and assuming that the surrounding light will be sufficient, as it was before?
Either way, this is why I think his first account is credible, i.e. no JonBenet.
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