Thank you all for comments, the 'pimping' and the tips!

I am thinking the dodge tool is something I should get round to playing with!
Just another couple of questions;
- To make the changes just to the sky, eg. to darken, would this have been selected* (lasso)? And then what? Or is it done by cloning?
* If it is by selection - are the trees included in the selection, or the bits of sky peeping through selected separately?
- Sharpening, with the 'pimps' above - would the whole image have been sharpened, or is it being done selectively. Until now, I've always sharpened the whole image. Should I making smaller selections? (by lassoing?)
Dabhand, could you let me know what changes you've made please. It all helps me understand what all the tools do. Thank you!