N53 (15) 1921 1R on 10pi red-brown Sweet Waters of Europe stamp of Turkey with "British Occupation" overprint, SG Type B (without Reshad, Iraq Issue), the release (without reshad) was never announced, thus the new issue dealers of the time failed to provide it to their clients, stamp catalogues did not list its existence until several years later, seriously undercatalogued mint as the vast majority were used postally or fiscally.
