I finally managed to win an auction on ebay for a vintage bicycle lamp from the 19th century, when bicycle lights were oil lamps or had carbide batteries. They seem quite popular for collectors as there is always a few on ebay and the bidding is always active.
This one ain't too pretty, one reason I didn't have much competition for it. It's also nickel plated instead of brass but I like it none the less. A little polish and elbow grease and the lamp will shine fine. The lamp has no lens but we can salvage one from another (modern) light or even fashion a lens.
As you can see in the photo the old reflector (the little round bit on the ground)normally in the back of the lamp is quite corroded. It may be salvageable but I might also replace it with the brass door slide handles you see pictured below with the lamp. The size and shape are perfect, and brass would give a warm glow.
I may also stuff the lamp with the battery pack, electronic innards and light array of a modern LED bike light, without modifying or harming the original lamp.