Perhaps it`s a Lancashire thing? My grandma was near Rochdale, and always said that you had to open the door so that the thunderbolt could roll down the stairs and oout the door. I never really knew what to believe about thunderbolts, but a couple of years ago, during a thunderstorm, there was a flash of lightening, our wi-fi router gave off a blue flame and smoke and gave up the ghost, plus at the same time, a large orange ball nof fire hit the wall at the end of the garage, all visible from where we were sitting. I`ve never seen anything like it before, and it cost us a new router.