I wouldn't be happy with that result. It's discolored. Not all furniture is going to last a lifetime.

You don't seem to know about Italian pull-up leathers. The toning effect is intentional.

@The KEEPING ROOM Can you change the color of leather this way if its a lighter color?

Yes, most definitely. But ONLY if its a pure aniline leather. You have to know what kind of leather you are working with. Most leather is finished, which means it has to be painted, Anilines are dyed.

I need to carefully check our pair of Hancock & Moore chairs! I try to keep a throw over the back, and the (light filtering) shades down in the living room so they're not getting any direct sun.

IIRC, they are 15 years old.

One of our sons has asked that they be left to him in our will for his law office!

@The KEEPING ROOM is there a way to identify whether tye leather is analine vs finished in another way? ty

It's not always easy how to identify an Aniline from a Finished leather, because the tanneries doing Finished leather have become very, very good and improved their product considerably. Generally, Pure Anilines (which are dyed leathers) are softer, show more variance in coloration, and are most natural looking (less processed). Aniine hides are not sanded down and impervections are left in the leather. Finished leathers are sanded down, the grain pattern is embossed into the leather, and they are painted.

You cannot dye a painted leather, they have to be re-painted. Anilines don't use paint, so they are indeed dyed. On older leather upholstery, painted leathers will look cracked and chipped in spots. Anilines will sun fade and absorb stains, that's primarily how you can tell

Thank you @The KEEPING ROOM, based on what you describe I'm guessing i have aniline. specifically your last sentence on fade and stain.