Reversing lights not working

Hi All
My reversing lights on my R26 aren't working and I suspect it's the switch, rather than the bulbs.
I say this because the bulbs were coming on intermittently, both together, and I assume that that wouldn't happen if the bulbs were at fault.
Can anyone tell me where the switch is please?
Thanks
Richard

 

Thanks for this Mike. I actually saw this video after posting. Quite a few people on the net seem to say it is underneath the battery tray, so I'll just have to look in both places. The car in the video isn't an r26 so I suppose it's possible it's different. I'll post back here when I've had a chance to have a look.
Richard