My thanks to
@juvela for bringing my attention to this thread! I realize it's an old one, and I have precious little to add, but I don't usually let that stop me....
1. I have seen this logo before, on a similar saddle, that appeared to be a quite old one. I'd guess these saddles are from before 1940 or so, but that's strictly a guess. I thought I had saved a photo of a saddle with this logo, but I can't find it now. It may very well be the same saddle.
2. I can't accept the Selle Anatomica suggestion. Selle Anatomica was founded in 2006 or something, and these saddles are much older.
3. I'm having a hard time accepting the Sturmey Archer suggestion as well. Sturmey Archer was, from its beginnings, part of Raleigh Industries; and their specialty was gears. Raleigh's saddles were made (and branded) by Brooks. I am not sure what kind of affiliation connected Brooks and Raleigh at that time, but clearly there was some kind of affiliation, and it just think it unlikely that Sturmey Archer would have made saddles or had someone else make them with Sturmey Archer branding. I realize this is not a strong argument.
I have looked through a lot of early Sturmey Archer advertisements and other literature, and I have not seen any reference to saddles or bicycle parts other than drive train gearing, hubs, dynamo hubs, and that kind of thing.
I have also failed to find this particular logo on any Sturmey Archer product. Sturmey Archer used an intertwined S/A on quadrant shifters:
but it's not quite the same logo as on the saddle. As far as I can tell, Sturmey Archer did not use that logo on any other product than the quadrant shifter, and they didn't use it on quadrant shifters for very long; they soon replaced it with a different intertwined S/A logo.
4. There was a firm in Birmingham that made saddles branded "Selle Anglaise." I have failed to learn anything about them, but I have a few photos of saddles with Selle Anglaise branding. Here's one:
I have not seen photos of any Selle Anglaise saddle with this S/A logo.
Okay, so, that's what I have. Pretty thin, eh? Still, if I had to put my money down on one option or the other, I'd bet on Selle Anglaise.