Golborne Vintage Radio

I agree about the LED.
They were constrained by the design of the existing lenses.
They would have had to rebuild the entire top of the lighthouse if they did it any other way.

I guess carbon arc was before filament lamps.
Oil lamps originally.

I think also they use a kind of Fresnel lens. A larger LED array would be problematical for creating a beam no matter what kind of lens. Hence LED torches have gone to single LEDs now, or what looks like a single LED so a suitable beam (or even "zoom") is possible. Multiple wider spaced LEDs would need an insect style set of lenses.