First was turning the sink, ripping down the old 'splashback', relocating the taps for the washing machine, and making a new ply splashback (which will have 3 or 4 coats of marine varnish for waterproofing)
And voila! A couple of days later and here's the new shelving system. I've now been able to move the cheese fridge (wine fridge bough at a garage sale for $25!) out of the guest bathroom :). I have loads more shelf space to play with, and it's a much better use of the space. We're hoping the new splashback will also seal off some of the more drafty areas of mud brick too.