Well greyghost has some traction.
I tend to start moving parts a little before there's time to work on them. Just to get a rough idea of where energies will need to be concentrated.
In this case i was trying to avoid the thought of making rails. & hoping the repairs would not be too onerous, either.
Now actually spent the evening doing some actual inspection and things are not that good.

The wood is probably a rosewood, as per BBC spec. Notice the fine black/smoky grain lines & general aspect of the grain. However, it is most likely
not classic BRW. Also seems even thinner than shown in the catalog. (FWIW, quite a bit harder/denser than walnut)
As greyghost observed, (though it does not seem to be stained), it could possibly have been "dye enhanced". I could not wash out a dark sample with lacquer thinner & scotchbright stripping pad, not would a rag pick up anything. It did make the color a little less dense, but that would be true of natural wood as well. Does not seem to be much more than wax on it. Though it would not have been uncommon to do a dilute wash coat of shellac for seal and shine before waxing.
My focus with the color Q was to figure out whether the original rails could be cleaned up & darkened if there was not too much damage. The way things are looking, not liking the answer a lot at this point. I'll stew on it for a couple days and take it back with the restoration post in the table tech forum. Thanks for bearing with me.
Overall view: from the front - unmolested rail, bleached out rail with penofin & "Tried & True" oil tests, actual BRW wood and shavings, rail that was attempted to wash out with lacquer thinner and scotchbright stripping pad. 8/4 lumber is cocobola (a true rosewood) for comparison.
Notice how thin the "hardwood" is over the poplar core.