Can anybody recommend a suitable brush on paint I can use to tart up the engine bay and chassis bits please or do I just get a couple of tins of smooth hammerite?
POR15 is very strong stuff, but a bit more expensive then hammerite, its designed to painted directly over rust, or bare metal, but its best to use a primer on very clean bare metal. Just don't get any on your skin, or anything else you don't want it on, as you can't get it off.
If they're small(ish) bits of steel, take them off and get them electroless nickel plated, either that or take a walk to Halfords and pick the colour acrylic spray of choice. Regards Iain