I have a Brooks B17 seats on our tandem bike. It is long since broken in and I find it very comfortable. The seat developed a "creaking" sound which was very difficult to localize on our Co-Motion Speedster. I was so convinced the sound was coming from the handlebar or stem area I dismantled everything and greased and lubed whatever I could reach. Nothing worked. Earlier, on the seat I used 3 in 1 oil on the rivets and bolts and nuts on the Brooks seat, so much that the oil leaked through the rivet and onto the leather. Finally, in desperation, on a recent tour I really slathered on chain lube oil on every possible place under the seat. The creaking stopped, but now I don't know which part was causing the creaking noise. Has anybody else had problems with a noisy B17 seat? I have another B17 on my touring bike and it never developed a noise.

Live with it. horseback leather saddles creak too.

Usually, but not always, when leather saddles creak, it's the nose piece. Either the tension bolt and nut, or where the nose is braced onto the rails. The other common place for squeaking is where the rails sit in the post. I also had an old Brooks Pro develop creak where the rear support sat on the rails (at 30,000+ miles) and eventually the brace cracked there.

Next time, don't get frustrated, and use some thinned oil (1 part oil, 5-10 parts mineral spirits) on one suspected place at a time, until you isolate the spot where it made the difference.

This has been my experience as well.

My solution is to hit it with a shot of silicone spray; I think it is less likely to affect the leather than anything petroleum-based and it stops the noise for months at a time.

Had a Flyer creak at the nose.
A small blob of Proofide + hair dryer turned the trick.

This is what I did to stop my B-17 from squeaking. I put one drop of oil where bolt threads meet, and took a flux brush to force some Proofhide in near the rivets from the underside.

Squeak stopped.....

One of mine started squeaking a few years back, stopped with a slight tighten of tension bolt, came back sometime later and despite trying different stuff, squeaked for a good long while and I almost got used to it. Tried putting proofide in a few places and it hasn't squeaked for a few years now. Cuz I tried multiple places at once, I'm not entirely sure which one did it.
Glad it stopped though, was annoying sometimes.

Thanks for the suggestions. Next time I'll give the front screw adjustment a shot of silicon spray and heat up some Proofride and flow it around the riveted areas.