I have put on the undercoat of GWR Signal Red on the insides of the frames.
It has gone alright but there are a few brush marks, even with my nice new sable brush, that I hope I will be able to improve on with the top coat.
I am reasonably relaxed about the appearance of the interior of the frames as they aren’t on show. Before I paint the outside I will appraise my abilities with the brush. Options are to spray enamel using the Badger 200 or to use Hammerite (Polly Model’s suggestion). The latter may well be the best option.