This is the first time I have tried stacking shots to produce a star trail rather than the somewhat more risky, eggs in one basket, guesstimate the exposure, long single exposure.

Are the stars and the Sun in their true relative positions? Seems a bit strange to me. Surely the stars revolve around Polaris (which is more or less true N) whereas the sun sets in the SW at this time of year, in which case the photo in the foreground is surely facing south of west.

Very observant John. The photo was taken in late May (setting sun in the NW) looking slightly west of north to get Polaris and the rotation. When you stack images you choose the image you want to 'add' the others to. My main image was the first in the series and there was still twilight which explains why there is still light in the sky. By the time I had stopped photographing it was dark apart from a tiny bit of brightness in the north west.