As I use my Zafira for work the nicer it is the better the day, so, having found the "how to" on additional interia lights I fitted LED lights in the front footwells also I fitted LED's in the front map lights, now a white light instead of yellow, so with some spare LED's I fitted a set in the back, as you can see
it fits quite well, having just checked it in the dark the results are quite good making it nice and bright.
It now comes on and off with the main back light and I can switch it on with the right hand switch.
Job done and only took half an hour + thinking time.