you can probably stop the squeaking by cutting a piece of inner tube and inserting it between the leather and the metal part of the frame... the part after the last rivet, on either side. You may have to get someone to hold the flap/side of saddle up while you do this. I haven't done it myself but I've heard it works.
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear