Avoid any petroleum-based products, including WD-40. Great for machinery, bad for leather.

Soaking in water is how the saddle was originally given its shape. I've made lots of leather items, including holsters, knife sheaths, arrow quivers, cell phone cases, etc. You soak the leather and then press it over a form and let it dry.

In your case, however, it should be sufficient to punch and lace the "wings," and pull them together from underneath the frame. Since the leather is old, do this SLOWLY and gradually after applying a leather dressing to the surface and letting it penetrate. Brooks actually sells some models (the Imperials) that have lacing to control the spread because of the central cut-away section. Check out their website for images.

Many people advise against leather dressings that contain silicone. Kiwi mink oil has a small amount of silicone in it, and I've used it for years with no bad consequences. Try a light application, let it sit overnight, then buff it off. I think the stuff is mostly lanolin, which Mother Nature uses to keep mammalian skin from cracking. I'm not familiar with Obenauf's - it may be just as good.

You said the saddle is already pliable, so no need to apply too much dressing. Over-softening can make the saddle stretch too much with use. Concerning the adjustment bolt, leave it alone unless the saddle is sagging fore-and-aft. Otherwise, if you run out of bolt threads, the saddle can never be tightened again! In your profile pic, I don't see that the saddle is sagging much in the middle. I have three fairly new B-17s that look about the same.

After you've laced it and applied some leather dressing, just ride it. Hopefully, it will conform to your sit bones over time. I haven't had to do this, but some people speed up the process by wetting the two sit-bone areas with water and pressing down on them with their thumbs to make slight depressions.

I'd be interested to know how you make out. Please keep us posted.

PS: If you want to see images of Brooks saddles that are beyond saving, Google Heinz Stuecke and check out his website. Each saddle has more than 100,000 miles on it.