Thanks guys. This is two photos taken at diffferent exposures, then blended carefully in Photoshop. I gave up using ND grads two years ago. Nothing wrong with them, but a little redundant with digital.
The light on the tower came from a 10 million candle power torch and a 30 second exposure. The blue sky was the colour of the cross over light that particular night. The trick to to make the colours and exposure right and look natural...none of the bizarre HDR colours in my portfolio!