Three watermarks seen on the 3d Wilding. The 3d with the Tudor watermark was only used in Tangier, and. The first major change for this stamp was the watermark, from the Tudor Crown to the St. Edward s Crown . The increase in the mail handled by the Post Office was so great, that improved handling methods had to be developed. The machine was used experimentally only in Southampton, using a method of electrical detection.
Coil join on graphite-lined stamp.
The next change was another alteration to the watermark from the St. Edwards Crown and cypher to the Multiple Crown watermark . The 3d Wilding definitive had more changes than most and the issue with the multiple crown watermark was the subject of most experiments over the years The graphite lines were also applied to the stamps with the Multiple Crown watermark. The graphite was not successful, so phosphor was tried, in addition to the graphite. The 3d stamp bearing two graphite lines on the back, and two side phosphor bands on the front was issued November 18, 1959. The phosphor appeared successful, so the graphite was discontinued in favour of phosphor bands.