Thanks Glen, actually Radar, the top left hand corner of the image is a crude clone attempt on my part to get rid of a part of my house's eaves that were in the way! Up close you can actually see the flyscreen in the image, and it didn't print particularly well. But a great storm nonetheless.
It was quite strange, I took approx 70-80 photos at 30", 15", 10" and bulb settings, but none turned out except this one, which was the very first shot. The others were just too light, it was literally daylight most of the time, and the shots looked like a normal sunny afternoon street scene.
Lightning shots are exceptionally hard to take, I think at least in my case you just need to fluke it!
My settings were:
Manual F3.5
Focal length 18mm
Shutter speed 30"
Tripod