I think Oldbeefer may have been referring to the Paines Wessex firework factory just off the 23 climbout lane at Boscombe. At the end of the working day, they would burn off any excess whizz bangs in a huge explosion that would light up the sky for miles around. Strangely enough, it didn't go down too well with the chaps conducting NVG ops on and around the airfield!
