Cheers everyone.
Prep on the models was, washed and scrubbed in hot soapy water, rinsed, dried, primed Matt Black and undercoated. Flaking paint lightly sanded off, soaked in rubbing alcohol, washed in strong detergent, rinsed, dried, primed with plastic primer, primed with normal primer and undercoated again. Still areas flaked. Vallejo Black acrylic primer is the only thing that sticks, about 10mm of varnish holding the rest on 👍
Truscott they were a light grey resin, all slightly different shades but light grey.
Regards Ken
The Yarkshire Gamer