This is one of my favourite 12V lamps so far. It has the simplest possible circuitry and would be perfect for implementing a whole house 12V lighting system that removed your reliance on external power for lighting, gave absolutely zero flicker lighting and with a suitable PWM dimmer, complete dimming from 0-100%.
Other things worthy of note. The simple circuitry means that the lamp will adjust its current according to the supply voltage and only put out its full power when a battery is being charged at around the 14V mark.

Comments:

I really wish they wouldn’t mix up voltages and fittings. E27 should definitely not be a 12V socket.

You’ve never spent time on big ships I can tell. I’ve had E27 lamps in 12, 24, 42, and 48V in addition to the “standard” 120V.

Still it’s a good idea to have separate standards for different stuff that isn’t directly interoperable.

The problem is you’re assuming E27 is connected to voltage. It’s not. It’s not connected to current either. There’s a huge difference in construction between a 40W capable and a 300W capable E27 sockets even if you forget about the voltage. The trouble with “idiot-proof” things is that they only get used by idiots.

Why do you think they’re not sold for use on boats and ships? Were you previously aware that E27 is common for 12V, 24V, 36V, 42V, 48V, 100V, 120V, and 230V lamps? I doubt it.

“The trouble with “idiot-proof” things is that they only get used by idiots.”