The RAF system was a clear bulb which was covered with the appropriate colour before installation inside the clear lens cover. So arguably even more efficient than having a pre-coloured bulb or lens.That’s coming on well Tony. Like the landing light conversion as well. The Japanese idea of clear bulbs in coloured acetate is far more logical than the British idea of coloured bulbs in clear acetate isn’t it. Far less spare bulb types needed in stores.
Modern aircraft use a similar setup, but I'm not sure if the bulbs are pre-coloured or not.