Dawes-man, I realize in your last post you have already (and rightly) rejected this type of option, but another brake that would be period correct and doesn't require drilling the frame is the Philco Centralpull such as this one that I had installed on my Fothergill for a while:
It clamps to the stays. It would be possible to put it under the chain stays. It's not a very strong brake (perhaps the fault of the levers I used it with), but it would probably satisfy the legal requirement.
Thanks for the suggestion, rhm. That's a pretty funky looking device and good to know about.
This is the look I'm aiming for:
[IMG]
IMG_5263 by
Dawes-man, on Flickr[/IMG]
In fact, when I get the Rotrax to Tokyo I'll be removing the components from this frame and fitting most of them to that. Then selling it as it's too small for me. This frame is drilled for a rear brake but the hole is filled with a reflector as I've been riding it fixed.