Vintage 8×10 glossy black and white half-length studio portrait, boldly signed and inscribed in black fountain pen, “To Elmer Newport/Best wishes/David Niven.”  Fine condition, with scattered very mild handling bends; small patches of silvering to some of the darker areas of the image, completely invisible when the photograph is viewed on; and an odd dark blob on the left lapel of his jacket — not an ink stain, definitely in the photo, itself — but why?