Thanks a lot guys
Carlos/Phil, it was visible as a faint white glow at that stage. Earlier on the curtains were more visible and the brightest ones a faint orange. The roll cloud was visible as a dark shape out to sea.
The timelapse is almost done. I had some camera issues...one fogged over half way through and another stopped writing to card at frame 27. I restarted the 2nd one later but the intervalometer died. Not good timing! Fortunately a 3rd got the whole display and stayed free of dew. Just working out how to splice together the footage I got.