Thank you Mateo.
For the benefit of anyone that's interested, I made a comment in a another thread regarding the overall blueness and I'll repeat it here, which should provide a bit more insight as to why these images appear the way they do:
Quote: The sky was very blue on Saturday, but I think the reason why it's come out SO blue is due to the film being Velvia 50 (known for bringing out very rich colours) and possibly because of the developing which I did myself. I followed the developer manufacturer's instructions to the letter, but it does allow for variation in the amount of time you can keep the film in the developer fluid depending on the conditions of the exposures.
I'll try experimenting a little next time, though I could also try de-saturating the blue a little in Photoshop. (ps. I did do a standard white balancing in CS3 and didn't increase the saturation as it clearly wasn't required - just WB, levels, highlight/shadows adjust and sharpening)