Thanks again guys. It is lit with a big searchblaster from Homebase (5MCP - about a tenner?) and camera on tripod. Exposure is about 30 seconds and once the shutter opens, lots of torch waving, concentrating on the distance mainly, with some "light painting" closer to the camera. These ones I actually got my exploring partner, the lovely Frogbox to stand at the opposite side of the tunnel doing the torch work as I liked the angle of light a bit better, as it gave more shadows. Hope that helps.