I did do some prep work. I had a bit of damage through falling off. I smoothed that out with a soldering iron then cleaned it well with soap and water. Still in the soapy water I lightly sanded it with very smooth "Wet & Dry" 1000 grade. This must be done with care. Too much rubbing or too coarse paper will make little balls of plastic on the surface. You just want to KEY the surface for the paint to stick. If it needs too much preperation work it's no good so only use a fairly good panel. Good to practice on a mangled one though. Once done and dried off, clean with methalated spirit and leave to dry over night.

That's what I did anyway and if I had a bit more patience it would have worked OK but as usual I went in like a bull in a china shop and rushed it.