Messing with shutter speed

Storms due so I have been trying (and failing) to get some lightning again! 

In the process I have been extending the shutter speed and using ND filters. Many thanks to DawnP for her advice! All sorts of things didn't happen but I did get a rectangle in some of the shots when there was lightning. No idea what that was, any ideas welcome. 

Anyway, I got this one which I liked. It is through the window so perhaps this reddish tinge is sunshine on the window at a long shutter speed. It was the best of a boring lot!