||The floodlighting of prestigious buildings at night has held great popularity since the first electric light sources of sufficiently high power were created. Naturally the majority of early installations made use of incandescent lamps, and a series of high wattage lamps in spherical bulbs with bunch-type filaments was made specifically for the purpose.
As the interests of lighting designers turned to coloured floodlighting, it was apparent that the combination of coloured filters with incandescent lamps was going to be a rather inefficient and expensive solution. Initially ordinary mercury and low pressure sodium lamps were employed to create colour contrasts, but in the 1950's a dedicated range of coloured lamps was produced. The first of these were MA Mercury products equipped with naturally coloured glass bulbs, to transmit just the blue, green, or yellow mercury lines respectively. Even these filtered sources lacked efficiency though, and a strong red light could not be produced by either mercury or sodium technology.
The GEC later created this linear neon lamp specifically as a red light source for the floodlighting of buildings. Similar tubes containing mercury and a phosphor-coated inner wall were offered in green and deep blue colours. The electrodes take the form of heavy tungsten coils, brought to continuous incandescence by a transformer circuit. A high voltage applied across the tube ionises the positive column of neon and a very large quantity of red light is produced. The bulbous tube ends are necessary due to the amount of heat generated by the continuously heated electrode coils. However in the late 1970's these tubes were discontinued, in favour of more efficient coloured metal halide products.