Thanks to all that helped. It was the light switch - such an important part made from stupid plastic. I managed to soldier the weak connection and it is working fine now - we'll see after a few bumps ! Secondly has anyone else had problems with the plastic coating coming off LR roof rack. I have had 2 in the last 5 years and they have both done the same. First the plastic cracks then starts parting from the metal frame work (then comes adrift at LR high speed travel!!!)