Soy milk works great in pancakes. My basic recipe for pancakes is about a cup of flour, about a cup of soy milk, a tablespoon or two of sugar and veg oil, and a few teaspoons of baking powder. Works great, makes nice, fluffy pancakes. (I know, not a "recipe" so much as list of ingredients with approximate proportions, but that's how I tend to cook, experimenting and learning from experience as I go...)
Edit: I don't know about scotch pancakes; I've never made them, but upon looking up a couple recipes, I don't see why it wouldn't... Soy milk behaves much like milk in these kinds of recipes, the only difference being that soya adds a bit of binding that dairy milk doesn't (and perhaps a smidge of a taste difference?)
Edit2: Haha, ok, so my "pancakes" are much more like your "scotch pancakes" -- there is such a wide spectrum of "pancakes", from crepe-y types to big, fluffy types... So then, yes, I'd say soya'd certainly work fine for scotch pancakes; for your "pancakes", I still suspect it'd be alright. With crepes mainly you just need liquid (hence the mixing with water in your posted recipe) -- the milk is mainly for some added flavour; I'd conjure that soya would work just fine.