About 3am, several flashes of light VERY similar to a strong camera flash or a Hollywood style lightning effect went off outside my window, lighting the whole room. I was awake at the time. I live in London, but my room backs on to quiet garden areas. I looked out of the window about a minute later. There was no storm and nobody around, it was very still, no noise and no movement. Yes, a neighbour could have taken a pic with a flash but I don’t think a flash from far away would cause the strength of this light. Also, there were no parties going on, nobody around. This is the third time it’s happened over 12 years, the last was about 3 years ago and I remember immediately googling what had happened and seeing quite a few posts about it. There is a road about 35 metres away parallel to my flat, but it’s a one way street and unlikely to be headlights from a car doing a 3 point turn. It’s a total mystery. The light is exactly like a strong camera flash from outside the window. Any ideas?