@francoise Agreed that it wasn't pitch black but the contrast between the brightly lit communications tower and the predawn sky produced this effect as the camera exposed for the highlights - which was indeed what I wanted. Sunrise was at 09:01 but the sky was heavy with cloud so it remained quite dull.
@vignouse yes I always forget that Europe is SO much further north than we are here. Sunrise 9:01! Here we're thinking it's late rising when it doesn't rise until 7:30.