The traditional "slackum" finish employed by English stockers of that period was heavy on linseed oil with chopped alkanet root steeped into the brew for some time to give it a decidedly red color, much like a fine red burgandy in appearance. When several coats are rubbed into the wood, it imparts a redish brown tone that is very popular. Very light or blonde finishes were not commonly seen. Find out what your finisher used, you might well be able to simply go over the top with several coats of something like the above brew to achieve what you are after. I prefer a mixture of tung oil and linseed, (75% tung/25% linseed or so) and leave the chopped alkanet root right in the bottle with the mixture. The bottle I am using now must be five years old at least, works very nicely. Others boil the root in alcohol first, then infuse it into the oil mixture. Either way works well. The alkanet root dye is what gives the walnut the nice reddish brown tone.
The finisher would not divulge his, "secret blend" of oils that he used to finish the stick with. I actually use a blend of Boiled linseed oil and Tung Oil using it in nearly identical proportions as you do.
I have heard of Alkenet root but have no idea of where to obtain this magical root. I would prefer to get an ounce or two of some oil that is already infused with it as to make a batch that will outlast my own lifetime. Any ideas of where I may locate this elixer?