Thanks for the comments.
@Philaitmen - I won't try to take much credit for composition here. What worked was more a lucky fluke than anything else

... I hadn't even spotted the aspect of the sky you mentioned

.
I'd hoped for a sunset, but it clouded over and I set off in the car to do some shopping. Suddenly the sun emerged & I had a few minutes to head for the nearest 'backdrop' I could find. I barely had time to get my camera on the tripod and snap away before it was all over. I had thoughts of getting down to the shore to find some foreground detail, but in hindsight I think this gave a better perspective anyway?
Here's another taken 5 minutes earlier (but I prefer the other one):