Thank you, Elsa, Akira and Hugh, for the kind comments.
Hugh - that is indeed a meteor (I was corrected about this not long ago, so I'm passing it on - a meteorite is a meteor which has made it all the way through to the earth's surface); a little earlier while moving camera position (of course!) I saw a spectacular one which flew all the way across the sky.
Akira - what you see is probably down to my uncertain and experimental processing. Also I have learned that the night sky can be very different in tone and colour, depending on which direction - n, s, e or w - you look, and whether the moon is in the sky. To the eye it all looks pretty much a dark background with pinpoint white stars, but the camera sees something quite different, and the longer the exposure the more the image will differ from what we actually see.