Newbold tunnel north of Rugby was illuminated in 2005. There are ten groups of three lights facing the offside wall. That’s 30 large sodium style lamps. 16 of these are defunct. So the ‘rainbow’ effect is not really apparent. The object of the lamps is to light the way through the tunnel for boaters (who have their own tunnel lamps) and pedestrians. Well the tunnel is only 185 yards long. It is quite well lit from natural light, but the time you really need the tunnel to be illuminated is after sunset and that is when they turn them off. Apparently there are bats that drink the water at night and they don’t want to disturb them. There is an old saying about about peoples inability to see the stupidity of their actions, ah yes, Blind as a bat!