"Thanks mate. Okay it's not as disasterous as initially thought - white spirit has removed most of it. But I think it will take some practice to get the desired effect. To be fair I didn't leave it for 15 minutes to dry - I left it for more like a couple of minutes, so I've obviously wiped off what was still wet. I take it you use a dry tissue to remove the wash and not a tissue soaked in white spirits?"
On a different note mate, what airbrush are you using? I seem to remember that you got hold of an H&S double action Evolution? If so, I reckon you could get a finer demarcation line (feathered edge) between any two colours you're spraying, I assume you're using acrylics as most ppl do nowadays and even I'm slowly going over to them. If so, what sort of dilution ratios are you using and are you using matt paints? I ask this 'cos I've started using the "gloss" range from tamiya and I'm now mixing up my colours which means firstly I can get them to look how I want them to, they're a gloss finish so decals go on the surface with no "silvering" at all, having much finer paint granules smaller amounts of paint pass through the nozzle without clogging, and its easy to matt the surface down afterwards rather than trying to make it glossier.
I've got hold of the all available primary tamiya colours, black, white, red, blue, yellow (though this a matt finish) and green and I can mix up some fairly accurate colours with those, and afterall, the colours darken anyway when washed with oil paint. I'm finding that when these are diluted quite heavily, say 30/70 paint /thinners, I can get in really close and have control to spray a very line, so keeping the scale effect feathered edge.