The 7-inch halogen headlamp is the established upgrade path for classic-MG owners who want substantially better lighting than the original sealed-beam units while keeping the visual appearance close to period-correct. The 7-inch round headlamp was the standard fitment across the majority of classic-MG production, the chrome-bumper MGB, the Midget through most of its production, the MGA, the MGC, and the early rubber-bumper MGB, and modern halogen units in the same 7-inch form fit directly into the original mounting buckets without modification, the H4 halogen bulb producing roughly three times the light output of the original tungsten or sealed-beam unit with a whiter, more natural light colour that improves contrast and depth perception at night.
Construction & Beam Performance
The 7-inch halogen units are stocked as pre-assembled conversions, each a complete unit comprising a steel headlamp bowl, steel inner body, retaining rim, retaining screws and bezel fixings, the E-marked H4 headlamp unit itself, an H4 halogen bulb, a sidelamp bulb where required, and a headlamp harness, supplied ready to drop into the existing headlamp bucket. The 7-inch halogen headlamp is constructed as a separate replaceable-bulb unit rather than the sealed-beam construction of the original, so when a bulb fails only the H4 bulb is replaced rather than the entire headlamp, and H4 bulbs are widely available from any motor factor. The convex lens focuses the beam more effectively than the original flat glass, projecting light further on main beam and providing a crisper dip-beam cut-off that illuminates the nearside verge without dazzling oncoming traffic, and the beam pattern is matched to UK and European left-side road-use specification, with RHD and LHD dip configurations available to suit the car.
E-Mark Compliance
Quality halogen headlamp units carry the E-mark certification indicating compliance with European lighting regulations, a small E-symbol followed by a country code visible on the lens, which confirms the headlamp meets the beam-pattern, intensity, and dispersion specifications required for UK road use and is an important consideration for MOT testing, where headlamp aim, beam pattern, and dazzle are all examined. Non-compliant headlamps, typically very inexpensive units imported from outside Europe, may not meet these specifications and can produce unsafe beam patterns, bright spots that dazzle other road users, dark spots that leave the road unlit, or incorrect cut-off lines that scatter light upwards into the eyes of oncoming drivers, so confirming the E-mark presence on any halogen unit being fitted is the right precaution.
Bulb Wattage & Wiring
H4 halogen bulbs are stocked in standard 60/55 watt, high-power 100/80 or 100/90 watt, Xenon-enhanced versions providing a whiter beam, and premium ranges such as Osram Silverstar offering up to 50% more light than standard H4. The original wiring loom was specified for the current draw of the original sealed-beam units, so the standard 60/55-watt halogen bulbs can typically run on the original wiring without modification, but higher-wattage bulbs draw substantially more current that the original wiring and light switch contacts may not handle reliably over long service. For high-wattage halogens, a headlamp relay kit is the appropriate precaution, running new heavier-gauge wires from the battery through a relay triggered by the original headlamp switch to the headlamps, so the original wiring carries only the low relay-trigger current rather than the full headlamp current, and a relay kit is strongly recommended alongside any halogen conversion in any case, as it delivers full battery voltage directly to the bulbs, recovering the voltage drop that decades of switch-contact wear introduces and prolonging switch life.