One of my Raleighs came with a sad old B17 (I think, could have been a 15) and I removed it for something else and it has sat in a parts bin since. It has some slight tearing on the forwardmost rear rivet on each side, the leather is a little flimsy and it generally wasn't in great shape.
I was thinking of trying out a Swallow or maybe getting a B17 and cutting it but remembered this saddle so I decided to practice on it. I still need to do a little straightening / evening out of my cuts and the cut should go higher up in the middle but I'm pretty happy with how it came out. I haven't taken it for a ride yet but but it feels pretty comfy.
I feel confident to try it on a nicer saddle now (with better planning and a sharper blade). I forgot to take a shot of the underside but will post one after I cut again. Anyway, here are a few pics.
(sorry for the flash photography and goofy lugless bike)
Not quite here yet...but hey it was my first shot