Interior light issue

I have a 99 Discovery SD and while I am driving my overhead light and steering wheel keyhole light will come on and off. I hear it may be some sort of short/relay problem but cannot find out what controls them. Any help would be welcome.

Might be the door switches shorting out. The switch makes contact when the door is open and will turn on the interior light (and presumably, the light for the key). If there's water or other contamination in the door switch it could be making an intermittent contact. Try taking the door switches out and investigating first.