I've not done any of the wagons, but I have had good results on the carriages with the Dulux spray can base coat. Although that was using the Dulux paints available in Australia, and I don't know if there's a difference between that and what's available there. I prepared the surface with very fine wet and dry and it applied very well. The only nuisance I found is that the factory seems to use whatever material is around at the time so there were differences in the plastic on two of the seven I painted (and in the material on the couplings on six of the seven!). Those two took a bit more effort to get a decent surface on, but the end result was still good.
-David Morris