Ever since the reporting of the St. Edward's Crown watermark error in September 1954, Commonwealth collectors have been searching for further examples of substituted and missing Crowns, broken or missing letters C and A.
In September 1954 Charles Rang reported his discovery of the substitution for a missing Crown with the St. Edward's Crown on a block of the 2c. British Guiana Postage Due issue of 1952. This error is today listed as SG D2ac, and is priced at £130. Another error was quickly found on the 16c. St. Lucia Postage Due, followed by another on the 1d. Basutoland. Discoveries of the error on postage stamps issued by the Seychelles revealed that the error was not restricted solely to postage dues. By October 1954 the search for the error was "being feverishly pursued all over the world", and some 33 different stamps from 9 colonies with the error had been identified. The error with the "missing Crown" was reported in the philatelic press in November 1954.
In recent times, discoveries continue to be made of examples with the "missing 'A'" and "missing 'C'" watermark varieties. Barbados is a particularly fertile area for these elusive errors, the definitive series of 1938-47 featuring no less than 7 "'A' of 'CA' missing from watermark" errors.
Murray Payne (http://www.murraypayne.com/) in their upcoming Philatelic Postal Auction #10 closing Thursday 22 September 2011 have listed as Lot 15 the following:
AntiguaThe pair is estimated to sell for £500.
15. 1949 UPU 1/- vertical pair, unmounted mint, showing 'A' of 'CA' in the watermark completely omitted, between the two stamps. Unlisted; the catalogue editors have been informed. SG 117 var./CW S11a
This is the first occurrence of this error on a stamp issue from Antigua.
Time to start checking all the Universal Postal Union Waterlow printings...