When built, early Marks were painted silver in all interior areas, including u/c leg tunnels, u/c door interiors, oleo legs, engine covers, fuselage interiors aft of the cockpit, and flap interiors. Wheel wells, themselves, are something of a mystery, since they are not mentioned on drawings, and nobody is clear whether they were seen as part of the interior, or exterior. This really means that you're spoilt for choice, with silver or the underside colour(s) being options, but not cockpit grey-green; only the cockpit, firewall and engine bearers got that as a coating. Note that none of the colours were primers; Spitfires used a light, or medium, grey as an undercoat, with the green, silver, or camouflage colours painted on top of that. Late in the war, or just after, silver was largely discontinued, and green spread to the interiors, but that might only apply to the 20-series, plus Seafires from the 15 onwards.