The interior lighting is modest by modern standards but functional when all components are working correctly, and is shared between the MGC and the contemporary MGB Mark II. The GT has the more complete arrangement, an interior roof lamp, a boot lamp activated by the tailgate, and a console lamp, with courtesy lights activated automatically by door-mounted switches. The Roadster has a simpler, often manually-switched arrangement by virtue of its open bodywork, but shares several components. On any car in service for decades, failed bulbs, cracked lenses, and faulty door switches are common and easy to overlook against larger restoration priorities, but they make a tangible difference to the usability of the car after dark.
Switches
The courtesy and boot lamp switches are the most frequent failure point in the interior lighting circuit. The door switch is a spring-loaded plunger type that compresses when the door is closed and extends when it opens, and corrosion on the plunger or a weakened internal spring causes the light to remain permanently on or off. A courtesy light that remains on when the door is closed will flatten the battery overnight if not noticed. Two variants of switch were used, a straight bullet connection type and an angled bullet connection type, and the correct switch must be identified before ordering as they are not interchangeable.
Lamps, Bulbs & Lenses
The courtesy light units are mounted in the cabin headlining and use festoon bulbs that are easily replaced by removing the lens. Festoon bulbs for the interior and boot lamps, and the smaller screw-thread bulbs for the console and map lamps, are all available individually. Lenses are available for the interior roof lamp, console lamp, and the combined number plate and map lamp unit, with the bright finish cover for the latter also available. LED alternatives are available for the door lamp positions in both red and clear, offering improved brightness and longevity over the original filament bulbs, and all associated fixings for lamp and lens installation are available alongside the components themselves.