Here's the finished half-sheet watercolour. I've made use of Titanium White as a bodycolour because it is more opaque than the traditional Chinese(Zinc) White. I'm not someone who holds strictly to the 'pure transparent' doctrine. The use of white 'bodycolour' has always been part of the watercolour tradition and it's use enhances the possibilities of the medium. You can play off opaque passages against transparent ones as Ken Howard does and it can be used to create crumbly textures on rocks and old walls. Only when it is thickly laid on like whitewash does it look out of place.