Another country heard from...

I used the Lexol (yet another leather conditioner, couldn't find any neatsfoot) method, that I think was recommended by Sheldon Brown when I first got my Brooks... wrap the top in foil, turn it upside down, add Lexol and let it soak overnight. Since then, I just use Proofide.

I don't treat it very often, but when I do I treat all leather surfaces that I can get to. I put on a coat thin enough that there's none that hasn't soaked in when I buff it a day later.

I can't say that this is the best, or even the right treatment, but after about 5 or so years the saddle is still doing fine. And that may be due largely to the fact that it's rarely gotten wet, except from perspiration, and not been exposed to much direct sunlight (when I'm not covering it, I usually put a plastic grocery bag or something over it).