classic motorcycle forum

Yes, I would regard a working (and visible) brake light in particular as essential in modern traffic.

Funny you should mention replica lamps. I've just taken delivery of several, and apart from no Lucas logos
or numbering they seem almost indistinguishable from the real thing. Sure beats an empty space, at least ...
Even the paintwork has improved lately ? 
We will see if they still work in 70+ years ?!

So where does this wee beastie get all the juice to power that big headlamp.
Not knowing lil RE's in the slightest ...

https://www.ebay.co.uk/itm/146989249719

Edit. Specs say it has Villiers direct (AC) lighting
And were new for 1933 ?

Hmmm, the Owners Manual for a later model refers to a 30w generator.

A wiring diagram for such a FB shows still no voltage  control.
But a large resistance wire - centre to the top - connected to the light switch.
To soak up unneeded power ?
When the lights are not in use ??

https://cybermotorcycle.com/gallery/francis-barnett-falcon-87/images/Francis-Barnett-1965c-Falcon-87-Wiring-Diagram.jpg

Be more sensible (these days) to have a lamp there as a running light. ?
Curious and curiouser ...

Interesting point.
This looking like less of a trickle charge, and more of a dribble charge ...

Indeed.
The local advertising for these was something like "a penny a mile"
so you couldn't get more economy oriented than that.

That said, you'd hope the engineering was at least in the ballpark,
And spares and a handbook gave you a chance of keeping it running ...

Now, to find a suitable Miller headlamp switch, for the best ! of all worlds
4 position, Direct as the 4th position.