b'34249249P 1931 Kingsford Smith Imperforate Die proofs of the 2d 3d & 6d stamps in the issued colours on wove paper recessed in a single thick card mount (200x150mm) with bevelled edges BW:141-143DP(2), minor damp spots on the mount, the 3d proof is superb; the 2d & 6d are affected by light staining from the adhesive used to affix them to the backing, Cat. $60,000. Unique! Ex Sir Harry Brown. The ACSC states these are the only finished die proofs for this series: there are no examples in the Australia Post Archives.Provenance: The Arthur Gray Collection, October 2015, Lot 419.$20,00025,000250250C March 1932 usage of 6d Kingsford Smith overprinted OS (+ unoverprinted 2d & 3d Harbour Bridge) on small registered airmail cover to New Zealand, the adhesives tied by multiple TOOWOOMBA (Qld) datestamps, black/blue registration label, on reverse TOOWOOMBA, BRISBANE & SYDNEY transits & WHAKATANE arrival datestamp. Elusive stamp on cover, Cat.$275. . $200250'