The switch is all the way forward I think for door-activated int. lights.
I don't know if your Bentley has wiring diagrams, but if it does, trace it. I would suspect either the door switches (the little rubber-booted thing chasis-side of the doorjam. Also, not your case if you replaced with good switches). Another suspect would be a supposed relay in the fuse box in the engine compartment, behind the firewall.
I think my passenger side footwell light has been on when I drive, but that's 'cause my glove box is on the floor in the back seat right now. And also, to be honest, one time when my interior lights were acting funny, I messed with my sunroof and the problem went away! It was weird. Check all your electrical connections