Fireworks?
I read quote from someone who lives nearby who said they were worried that they might have been responsible because they were having a fireworks party at the time and they thought one of their rockets might have hit the turbine. So we've got someone having a fireworks party and there are strange lights in the sky and a "big bang" - nah can't be any connection must be a UFO.
Paris 'cos she's always willing to give us a flash, and she likes a good bang.