Not 6 - never used that area for night work. Had enough difficulty getting clearance to use lepus flares on Wainfleet and Otterburn. Curious that in both of those places where complaints could have been expected, there were none. Have to conclude that if you use 'pretty' parachute flares the public quite like it.
Maybe the flashes that went bang at Thetford were recce photoflashes?
Must say that in those days I would have preferred to also be in the pub at Griston - or another in lieu.