Ronseal Yacht Varnish Satin appears to be a pretty good match. This is 3 coats on the test piece, next to the original Bavaria varnish from 2001 (the table edge). The satin is slightly less glossy than the original, but close enough (they make a gloss version, but I think that would be far too glossy then, and I don't want to bother mixing my own).
The Ronseal is a smelly synthetic varnish and not nearly as tough as the original (which I've just scraped off the test piece - didn't come off easy). There is no wood stain (the Sapele really is that dark) and the varnish is a clear(-ish) one without additional dyes. The original varnish was sprayed on and was probably a UV curing industrial varnish so that many coats can be applied in a short time (a pass through a high powered UV light instantly cures this type of varnish).
Good enough for me I think and will get some more to do the companionway steps this spring.