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.
